The invention discloses a cement kiln denitration discharge method. A preheater system, a kiln tail smoke exhaust pipeline, smoke treatment equipment, a high-temperature fan and a kiln tail dust collector of an existing dry-method cement kiln are utilized. The method comprises adding a catalyst into kiln tail flue gas at an outlet of the preheater system, after the catalyst and the flue gas are mixed, catalyzing the flue gas containing the reducing agent and the nitric oxide to be subjected to a denitration reaction, collecting the catalyst at a kiln tail dust collector, making the catalyst and the raw material pass through a raw material elevator and enter into a preheater system, catalyzing the flue gas containing the reducing agent and the nitric oxide to be subjected to the denitrationreaction, wherein the reducing agent is an ammonia compound or an amine compound, and adding at a reducing agent filling point newly arranged on the preheater or adding by utilizing an existing SNCRsystem. The invention has the characteristics of low investment, low operation cost, no blockage, no poisoning, high reliability and the like.