The invention discloses a method for solid degumming of broussonetia papyrifera bast fiber. At a temperature of between 30 and 40 DEG C, a microbe is used for degumming the broussonetia papyrifera bast fiber containing little water; the pH value of water solution of the broussonetia papyrifera bast fiber is between 5 and 9; the mass ratio of the broussonetia papyrifera bast fiber to water isbetween 1:-3; bacillus subtilis is preferably selected as the microbe; when bacteria solution of bacillus subtilis is used, the adding volume of the bacteria solution of microbial bacillus subtilis is 3 to 10 percent (V/V) of the total volume of water; and the degumming time is 1 to 6 days. The degumming method provided by the invention has the advantages that: the waste water generated in degumming does not contain any chemical residue, and does not cause any environmental pollution; and the residual gum ratio of a fibrous raw material obtained after the degumming and used for paper making and spinning is 0.1 to 0.6 percent; and compared with the prior process, the long-fiber ratio is improved by 10 percent. Because the improvement of the resource utilization ratio and the reduction of the environmental pollution are achieved at the same time, the method has wide application prospect.