The invention relates to the technical field of fire grate of layer-burning boiler, in particular to a combined fire grate capable of realizing complete bottom fire, and aims to solve the technical problem that in the layer-burning boiler, the existing combined fire grate structure comprising a vertical type reciprocating grate and a chain grate cannot provide complete bottom fire for the fuel on the chain grate, so as not to achieve sufficient burning efficiency of the boiler. The adopted technical scheme is as follow: the combined fire grate capable of realizing complete bottom fire is provided and comprises the existing vertical type reciprocating grate and chain grate, wherein a fire blowing device is arranged between the lower end of the vertical type reciprocating grate and the front part of the chain grate, and comprises a hollow shaft with one plugged end and backward leaning fire blowing tube rows which are distributed in groups and surrounding the surface of the hollow shaft; the plugged end of the hollow shaft is connected with a transmission coupler, and the other end is matched with a corresponding end of a packing seal component connected with an outlet of a high-pressure air pipeline.