The invention belongs to the technical field of a boiler denitration device and especially relates to a mixing distribution device for a power station boiler SNCR denitration system. The invention mainly aims to solve the problems of low denitration rate, high ammonia escape volume and low boiler heat efficiency of the present SNCR denitration system. The mixing distribution device for the power station boiler SNCR denitration system provided by the invention comprises a power station boiler, an SNCR denitration system connected with the power station boiler, a plurality of spray gun reducing agent control units and a plurality of compressed air control units, wherein each spray gun reducing agent control unit is matched with each compressed air control unit so as to form one set and each spray gun reducing agent control unit comprises a reducing agent solution, softened water, a plurality of solenoid valves, a plurality of adjusting valves, a plurality of flow meters, a buffering mixer and a plurality of spray guns.