In our clinic, we often encounter many parents of children with lacrimal symptoms at birth or soon after birth, with the onset of lacrimation in one or both eyes and yellow mucopurulent discharge, mostly diagnosed as “lacrimal duct obstruction combined with dacryocystitis”. To understand the cause of this disease, we must first look at the developmental process of the lacrimal duct: during fetal development, the lacrimal duct begins to form gradually after the sixth week of embryonic development, the upper and lower tear dots open in the seventh month, and the lower nasolacrimal duct opens in the eighth month. The Hasner valve at the lower end of the nasolacrimal duct is like a door, and its role is particularly important. Congenital lacrimal stenosis or obstruction is caused by the non-opening of the Haner’s membrane flap. Tears and secretions cannot be drained through the tear duct and accumulate, and when combined with viral or bacterial infections, they form a dacryocystitis, with a large amount of purulent discharge.