In this study, in-line X-ray phase contrast imaging was used to visualize a lung of an intact mouse. Our findings showed that IL-XPCI had the ability to represent complex anatomical structures in lungs. The three-dimensional model of lungs has been successfully established which provided an excellent view of lung airways. Thanks to the high resolution of the imaging, deep study was carried out on the tiny alveoli. A full understanding of the alveoli's architecture can facilitate the study of respiratory mechanism on the alveoli level. Single alveolus was displayed and measured. This offers a new perspective on the diagnosis of respiratory disease. Pathological changes can be detected by measuring the size of the lung airways, although further research and experimentation on lung is required to test this hypothesis.