The utility model discloses a double fluidized bed solid fuel gasification combustion coupling system, which includes a bubbling bed gasification reactor and a circulating fluidized bed boiler; a solid semicoke outlet of the bubbling bed gasification reactor is communicated with the circulating fluidized bed boiler through a first solid return device, and a coal gas outlet of the bubbling bed gasification reactor is communicated with a coal gas heat exchange device; a smoke outlet of the circulating fluidized bed boiler is communicated with a smoke separation device; a solid outlet of the smoke separation device is connected with a heat carrier inlet of the bubbling bed gasification reactor through a second solid return device, and a smoke heat exchange device is arranged at a gas outlet of the smoke separation device; and the coal gas heat exchange device and the smoke heat exchange device are communicated with a gasification agent inlet of the bubbling bed gasification reactor. Through combing the bubbling bed gasification reactor with the circulating fluidized bed boiler, the system realizes the continuous and stable running of the gasification combustion coupling process and the poly-generation of water gas (semi water gas) and steam.