Abstract: In order to take full advantage of cellulose in plant residues, three strains (ZWY-3, DP-6 and DP-8) of cellulose-decomposing bacteria were isolated from the humus-rich soil by the medium with the sole carbon source of CMC-Na and Congo red screening method. Enzyme activity was measured under different incubation time, temperature, original pH and carbon source. The results showed that three strains showed the highest cellulose activity under the condition of 24 h, pH 7, 30℃ and glucose as carbon source, DP-6 had the highest cellulose activity of 144.86 U when the incubation time was 24 h, ZWY-3 had the cellulose activity of 126.74 U when the incubation temperature was 30℃, and the highest cellulose activity of 133.82 U when the pH value was 7. DP-6 showed the highest activity of 218.96 U when cultivated under the optimal condition with glucose as the only carbon source. These three strains showed great potential in the industry of agricultural cellulose-decomposing.