This study almed to screen a highIy efficient ceI uIose-degrading compIex microbial system from soiI and rotten straw and then study its appIication to natural ceI uIose. The isoIated stralns were preIiminariIy screened with Congo red stalning and the ceI uIases activities were determined with DNS method. The non-antagonis-tic highIy efficient ceI uIos-degrading stralns were seIected and cuItured combinedIy for deveIoping a ceI uIose-degrading compIex microbial system. The resuIts showed that the CMC enzyme activity of the mixed cuIture of the three fungi stralns was higher than those of the cuItures of the three singIe stralns. The morphoIogical and moIecuIar bioIogical identification indicated that F1 was Botryosphaeria, F2 was Rhi-zopus oryzae, and F5 was Fusarium oxysporum. When straw was used as carbon source, the CMC enzyme activities of F1, F2 and F5 were 39.2, 31.4 and 40.6 IU/mI, respectiveIy; whiIe the CMC enzyme activity of the mixed cuIture of F1+F2+F5 was 50.12 IU/mI, which was increased by 23% compared to that of the singIe straln of F5. The experimental resuIts indicated that the ceI uIose-degrading effect of the compIex microbial system was better than those of the singIe fungi stralns, and the singIe stralns of F1, F2 and F5 had certaln deveIopment potentials.