Babies always tearing in one eye may be caused by tear duct obstruction and conjunctival foreign bodies. 1. Lacrimal duct obstruction: the lacrimal duct is the channel through which tears pass, and under normal circumstances, tears flow from the tear ducts, lacrimal sacs, nasolacrimal ducts, into the nasal cavity. If the tear duct is blocked (such as congenital nasolacrimal duct blockage), it is difficult for tears to circulate through the tear duct and flow back into the body, but only outflow from the eye, resulting in babies always tearing up in one eye. 2. Conjunctival foreign body: eyes into the sand, eyelashes or other foreign objects (including conjunctivitis caused by inflammatory substances) will irritate the conjunctiva, discomfort symptoms, stimulate the secretion of tears, manifested in the symptoms of one eye tearing. Baby one eye always tearing can be gently massage the nose at the beginning of the bridge of the nose, dredge the tear ducts, if the symptoms have not been able to alleviate, please take the baby to the ophthalmology consultation.