The invention belongs to the technical field of biomass energy processing and large-scale utilization, and particularly relates to a material stirring device for a biomass bin. The device comprises a transmission mechanism, a main stirring mechanism and an auxiliary stirring mechanism, wherein the main stirring mechanism comprises a cylinder, and a hollow stirring rod is arranged on the outer wall of the cylinder; the cylinder is connected with the transmission mechanism, and the auxiliary stirring mechanism comprises a rotating shaft which vertically penetrates through the hollow stirring rod; the two ends of the rotating shaft are provided with stirring blades, and the rotating shaft is connected with the transmission mechanism. The material stirring device provided by the invention has the advantages that the structure is simple and the design is skillful, a biomass material in the bin is reasonably stirred, and the defect that the stirring device is easily damaged due to too high density of the biomass material is overcome; through the automatic conversion and adjustment of the main stirring mechanism and the auxiliary stirring mechanism, the organic combination of overall stirring and local stirring is realized, the continuous discharging efficiency of the biomass material in the bin is improved, the requirement of industrial application of the biomass material is met, the processing efficiency of biomass is improved, the environmental pollution is reduced, and the large-scale utilization process of biomass energy is quickened.