Natural compost was used as a source of bacteria and cellulose was the only carbon source. After initial screening, secondary screening, and molecular biology identification, X11 belonged to the Pseudomonas sp., Z3 and Z25 belonged to the Cladosporium sp., and F74 belonged to the Streptomyces sp. Based on the mixed study of three types of cellulose-degrading bacteria, it was found that the filter paper degrading enzyme activity of the X11F74 was 0.327 IU/g, the carboxymethylcellulose (CMC) degrading enzyme activity was 1.312 IU/g, and the microcrystalline cellulose enzyme activity was 0.289 IU/g, significantly superior to other combinations, demonstrating synergistic effects. The optimal conditions for enzyme production by X11F74 CMC were determined by a one-way variable test to be an incubation time of 5 d, an initial pH of the medium of 6, an incubation temperature of 20ºC, and an inoculum of 5%. Finally, the mechanism of cellulose degradation by X11F74 was analyzed.