Lacrimal duct obstruction is a localized lesion in the lacrimal duct that normally drains tears, resulting in obstruction, narrowing, or dysphasia in different parts of the lacrimal duct. The causes can be developmental abnormalities of the lacrimal duct, trauma, or inflammatory infections. First, the most common developmental abnormality is neonatal dacryocystitis. Because the lower valve of the nasolacrimal duct is not completely open, the tear drains into the throat and the baby shows constant “tearing”. As the tear duct is not open, it can easily cause bacterial infection and lead to neonatal dacryocystitis. The main treatment is regular pressure on the lacrimal sac and most patients can open it on their own. For patients who cannot open, a lacrimal ductal exploration will be performed to determine the specific situation, and if the lacrimal ductal exploration still fails to restore, relevant lacrimal surgery will have to be considered. In adults, the most common cause is due to lacrimal dystrophy, with chronic lacrimal dystrophy being the main type. The main manifestation is tearing accompanied by increased secretion, which often lasts for a longer period of time. A lacrimal duct irrigation examination is performed to clarify the specific site of obstruction, and the final result in most patients requires surgical methods, such as lacrimal duct placement, but the results are not guaranteed for reocclusion due to recurrence of inflammation. The nasal lacrimal sac anastomosis is relatively the most effective procedure. There are many reasons why lacrimal duct obstruction can occur, the common factors are developmental abnormalities or infections, and the ultimate treatment is surgery.