A duct for tear flow, for connecting the nasal cavity and the lacrimal sac, comprises: a tube, which is set across the nasal mucosa, nasal bone wall and lacrimal sac mucosa, so that the nasal cavity and the lacrimal sac are connected a positioning element, set on the front of the tube, and fastened on the lacrimal sac mucosa so that tears flow into the nasal cavity due to a connection between the nasal cavity and the lacrimal sac.
