The invention discloses an integrated solid state fermentation reactor. The reactor comprises, sequentially connected, a charging system, a fermentation tank and a rotary vacuum double-cone drying machine; and the charging system comprises, sequentially connected, an electric motor, a charging hopper, a conveying screw and a discharging tube, a stainless steel jacket is welded on the outer wall of the body of the fermentation tank, and the fermentation tank is also provided with a gas outlet, probes, a steam inlet, a steam outlet, a discharge opening, movable top covers and a two-fluid nozzle device. The invention also discloses an application of the reactor in solid state fermentation of aerobic, anaerobic and facultative anaerobic microbes. Compared with reactors in the prior art, the reactor has the advantages of high automation intensity, stable fermentation process, simple operation, realization of single-batch and multi-batch fermentation production, and facilitation of industrial application of solid state fermentation.