The invention discloses a method for in-situ saccharification of bagasse with ion liquid resistant galactomyces sp. and cellulase of ion liquid resistant galactomyces sp., and belongs to the technical field of microbiology. The cellulose tolerant to (IL) 1,3-[Mmim]DMP generates Galactomyces sp.; the cellulose metabolized by the Galactomyces sp. can be tolerant to [Mmim]DMP; and when [Mmim]DMP with 5%(v/v) is added to a culturing system and [Mmim]DMP with 25%(v/v) is added to a reaction system, the cellulase still shows higher activity. In addition, the cellulase can realize highly efficient in-situ enzymolysis of the bagasse. Compared with the existing two-step method that the regeneration enzymolysis is conducted after the bagasse is processed by ion liquid, the method is simple in technology, and has the advantages of high efficiency, economical course, less three wastes (waste gas, waste water and waste residue) and the like.