Chronic dacryocystitis is a common and frequent disease in ophthalmology, and the results of conservative treatment with drugs are mostly unsatisfactory and mainly rely on surgical treatment. Since the invention of the lacrimal sac nasal anastomosis by the Italian surgeon Toti, the procedure has been recognized as the most ideal method for the treatment of chronic lacrimal sacculitis. However, the lacrimal sac nasal anastomosis performed from the skin of the face can cause facial scarring, possible displacement of the tear dots, severance of the medial canthal ligament and damage to the orbicularis oculi. After more than 100 years of development, the treatment of chronic dacryocystitis has evolved considerably. The transnasal endoscopic lacrimal sac nasal anastomosis performed in recent years has become increasingly sophisticated. Due to the rapid development of nasal endoscopy, transnasal endoscopic treatment of chronic dacryocystitis has become one of the important elements of nasal and ocular related surgery. Compared with traditional extra-nasal lacrimal sac nasal anastomosis, this procedure has the following advantages: 1. Transnasal endoscopic lacrimal sac nasal anastomosis effectively avoids facial scarring, does not require cutting the medial canthal ligament, causes little damage to the lacrimal sac and preserves the tear pump function of the lacrimal sac, allowing tears to be drained in a near physiological manner. 2.It can simultaneously deal with nasal sinus diseases or anatomical abnormalities such as sinusitis, nasal polyps, vesicular middle turbinate and deviated nasal septum to remove the cause, increase the success rate of surgery and eliminate the hidden danger of recurrence after surgery. 3.The surgery can be performed accurately under the nasal endoscope, and the position, size and opening of the bone hole can be directly observed without affecting the beauty, less bleeding, high cure rate, low recurrence rate and no complications. 4.The surgery is convenient and the access is short. There is only a thin bone separating the medial wall of the lacrimal sac and the front of the middle nasal passage, so the operation time is shortened. 5.Less damage, less pain for patients, light postoperative reaction, no need to fill the nasal cavity. 6. Both eyes can be operated at the same time. 7.The indications for surgery are wide, and it is still effective for cases where conventional surgery fails. It is worth mentioning that in the past, acute dacryocystitis was thought to require lacrimal sac incision and drainage at the abscess site on the basis of anti-inflammation and anti-infection, and then lacrimal sac nasal anastomosis surgery after sufficient anti-inflammation and decongestion. Transnasal endoscopic lacrimal sac nasal anastomosis can be performed in the acute stage of lacrimal sac incision and drainage, which can effectively shorten the course of the disease, and the treatment effect is very satisfactory.