The invention discloses a backflow and airway damage preventing sterile sealed sputum suction pipe. The sputum suction pipe comprises a negative pressure connecting pipe, an annular protrusion, a negative pressure adjusting backflow preventing device, an adjusting button, a sterile sputum suction pipe, a backflow preventing device, a damage preventing liquid inlet end, a main attracting hole, a side guiding hole and a protecting body. The purpose is to solve the problems that holes in the side wall of the pipe adhere to the pharyngeal portion or the airway mucous membrane when negative pressure attraction is conducted, the mucous membrane deforms and protrudes into the side wall holes causing hyperemia oedema to block the airway, sputum liquid backflow in the pipe easily takes place aftersputum suction, sputum liquid backflow takes place to cause contamination, and the negative pressure in the sputum suction pipe cannot be easily controlled after a negative pressure machine is conducted.