The lacrimal endoscope is applied to the diagnosis and therapy of the disorders of the lacrimal system in combination with laser or micro drills under orthophoria. The changes of mucous membranes, the characteristics of pathological changes and the predilection sites of lacrimal system diseases were initially approached. One hundred and forty six pairs of eyes of 128 patients with lacrimal system disease were observed by the lacrimal endoscope in the Ophthalmology Department of Tongji Hospital from June 2006 to March 2007. The dynamic changes in mucous membranes, lesion sites, secreted substances and formation of membrane could be observed under orthophoria. Combined with laser or micro drill, the endoscope was applied to the therapy of lacrimal system disorders and the difference before and after the treatment was observed. Results are as follows: (1) The examination and therapy using the lacrimal endoscope were completed under topical anesthesia in 122 patients, and 6 patients of neonatorum dacryocystitis were examined and treated under general anaesthesia. All patients reported painless. (2) Sharp images of the lacrimal system were obtained by the endoscope. Normal lacrimal mucosal membrane was smooth and light pink, expanded and unobstructed during irrigation. In chronic dacryocystitis patients, the inhomogeneous colour of mucosal membranes was red and white, with different degrees of fibrotic membranes at the superior, middle and inferior parts of the nasolacrimal canals and secreted substances at sac could be observed. The lacrimal ducts could not be expanded and obstructed during irrigation. The patients with lacrimal system obstruction had different extents of membrane formation, and stenosis or complete obstruction of the lacrimal duct could be observed, and the corresponding mucosal membrane was not smooth which could not be expanded and obstructed during irrigation. (3) After the treatment by the endoscope combined with laser or micro drill, the major proliferation of the membrane disappeared and the lacrimal duct was unobstructed during irrigation. The cure rate and effective rate were 80.1% and 93.1%, respectively. The lacrimal endoscope is a new method in the diagnosis of lacrimal system diseases. Through a combination with laser or micro drill to carry out the therapy under orthophoria, it will bring a great change to the diagnosis and therapy of lacrimal system diseases.