Inclusion Criteria:  1.Age between 18 and 65 years old. 2.Patients scheduled for laparoscopic radical resection of liver cancer under general anesthesia. 3.Patients ASA classification Ⅰ-Ⅲ. 4.Body mass index 18.5 kg/m2 ~ 24.9 kg/m2 5.Able to give informed consent. 6.The surgical position is suitable for BIS monitoring and muscle relaxation monitoring.  Exclusion Criteria:  1.Patients with allergic to rocuronium and SUG. 2.Patients with central and peripheral nervous system diseases, such as polio, Parkinson's disease, peripheral neuropathy, etc.. 3.Patients with neuromuscular system diseases, such as multiple sclerosis, myasthenia gravis, atrophic myotonia, etc.. 4.Patients with diaphragm dysfunction, pneumothorax, pleural effusion, mediastinal pneumatosis. 5.Pregnant women or nursing mothers. 6.Judging by the researchers, patients with other conditions who are unsuitable for clinical trials.