Colorectal cancer (CRC) is a malignant tumor originates from colorectal mucosa epithelium. It is one of the most common malignant tumors in the world. Incidence rate of lung cancer is second only to lung cancer and breast cancer worldwide. In recent years, with the continuous improvement of people's living standard, changes in diet and diet structure and aging of population, the incidence rate and mortality rate of colorectal cancer in China have been increasing. A significant proportion of colorectal cancer patients have no characteristic clinical symptoms and reported symptoms. Many colorectal cancers have reached the middle and late stage when they are discovered, and their prognosis is poor. It can be seen that early prevention of colorectal cancer is very important. Timely screening for colorectal adenomas and endoscopic resection are the most effective measures to prevent colorectal cancer. Colonoscopy is currently recognized as the gold standard for colorectal cancer screening, which can not only detect early precancerous lesions, but also remove precancerous lesions and block the formation of colorectal cancer.Colonoscopy is an important means of screening, diagnosis and treatment of colonic diseases. The accuracy of diagnosis and the safety of treatment are closely related to the quality of intestinal preparation. Adequate intestinal preparation can make patients obtain higher intestinal cleanliness, ensure the integrity and correctness of colonoscopy, improve the detection rate of polyps and adenomas, increase the rate of cecal intubation and reduce the follow-up time The occurrence of adverse events such as shortened interval, intestinal perforation and missed diagnosis is of great significance for the realization of high-quality enteroscopy diagnosis and treatment.Bowel preparation is not a simple cathartic process, it involves all aspects of communication between patients and doctors. Good intestinal preparation includes following dietary restrictions before examination, applying adequate amount of appropriate cathartic drugs during intestinal preparation, waiting for the appropriate time interval between colonoscopies after intestinal preparation, and appropriate amount of active drinking water, etc. Strict dietary restriction and bowel cleaning are the necessary conditions to improve the quality of bowel preparation. Kang x et al. Showed that 18% to 30.5% of patients had insufficient bowel preparation \[. Clinically, there may be more patients with poor bowel preparation. Inadequate bowel preparation will lead to longer operation time, more difficult catheterization of cecum, lower detection rate of adenoma and shorter follow-up time, which will increase the cost of colonoscopy. At present, Boston scale is widely used to evaluate the quality of intestinal preparation. The Boston scale divides the colon into three segments (cecum and ascending colon; hepatic, transverse and splenic flexure; descending, sigmoid and rectum). According to the worst-case to clean score, it is divided into four grades (0-3), with a total score of 0-9. Boston scale ≥ 6 points indicates that the intestinal preparation is qualified.There are many factors that lead to poor bowel preparation. Recently, a number of studies at home and abroad have evaluated the risk factors related to insufficient bowel preparation. Obesity, men, older age, previous colon surgery history, accompanied by other diseases (such as diabetes, Parkinson's disease), taking antidepressants and other factors can affect the effect of bowel preparation. Combined with the literature at home and abroad and the characteristics of Chinese people, the guidelines for gut preparation related to the diagnosis and treatment of digestive endoscopy in China suggest that the following factors are the risk factors for inadequate gut preparation in China: chronic constipation, failure to prepare the gut in strict accordance with the requirements (such as high fiber diet before operation, insufficient peg intake), body mass index \> 25 kg / m2, age \> 70 years old, colon surgery history With other diseases (such as diabetes, Parkinson's disease, history of stroke or spinal cord injury, etc.), application of tricyclic antidepressants or anesthetics.In addition, the guidelines for gut preparation related to the diagnosis and treatment of digestive endoscopy in China suggest that if the patient's gut preparation is not sufficient during the endoscopic examination, it should be actively evaluated and remedial measures should be taken or the endoscopic examination should be rescheduled. For the patients with the risk factors of insufficient intestinal preparation, other auxiliary measures can be taken to improve the intestinal preparation, such as the 4L peg program, low residue diet three days before endoscopic diagnosis and treatment, gastrointestinal motility promoting drugs, etc.; in addition, it is also of great value to further strengthen the education related to the optimization of intestinal preparation for the patients.In recent years, with the continuous development of China's economy, the continuous improvement of people's living conditions, and the continuous strengthening of patients' health awareness, colonoscopy has become one of the necessary items for many people's routine physical examination. However, in most medical institutions, when guiding patients to prepare for intestinal tract, there are some problems, such as lack of management, lack of detailed explanation, and complex process. These problems lead to the lack of understanding of intestinal tract preparation process for patients, thus affecting the preparation work before patients' examination and the follow-up treatment plan. Therefore, it has become one of the most important issues to study how to improve the intervention and guidance methods of patients' intestinal preparation and improve the quality of patients' intestinal preparation.Although the research of intestinal preparation intervention and education methods has made a lot of progress, various methods of intervention and guidance for patients before colonoscopy have been proposed at home and abroad to improve the quality of intestinal preparation. However, in a series of reports, there are still a considerable number of patients in the colonoscopy problems of intestinal preparation.At present, there are few researches on individualized intervention aiming at the risk factors of inadequate bowel preparation in China, so it is urgent to explore individualized bowel preparation programs suitable for different populations. Therefore, in this experiment, we designed individualized intervention for patients with insufficient bowel preparation (mainly from the following aspects: chronic constipation, not strictly in accordance with the requirements Bowel preparation, body mass index \> 25 kg / m2, age \> 70 years old, with other diseases such as diabetes, Parkinson's disease, history of stroke or spinal cord injury, application of tricyclic antidepressants or anesthetics). The purpose of the study is to study the effect of individualized intervention on the quality of intestinal preparation for patients with insufficient intestinal preparation, and to provide reference for improving the quality of intestinal preparation for patients with insufficient intestinal preparation.