A strain with highly efficient to degrade cellulose was screened from straw returning soil, termed CMC-4. This strain was identified as Bacillus licheniformis by 16S rRNA gene sequencing, physiological and biochemical properties. Using sodium nitrite as mutagene, a mutant strain CMC-4-3 with stable high-cellulase producing was obtained. The enzymatic prope?rties and enzyme producing conditions of CMC-4 and CMC-4-3 were analyzed. The results showed that cellulase activity of CMC-4-3 was two times as that of CMC-4. And the optimal conditions for enzyme producing of CMC-4-3 were as follows: medium Volume 60 ml/250 ml, inoculation size 2.0%, source of carbon glucose, nitrogen source peptone, the optimum temperature 37 ℃, optimum pH 6.0. The optimal pH and temperature of reaction for the cellulase were 6.0 and 50 ℃, and the enzyme activity was stable at the ranges of pH from 4.0 to 7.0 and temperature from 20 ℃ to 80 ℃. Fe²⁺, Mg²⁺, Co²⁺ and K⁺ could activate this cellulase, while other metal ions had some inhibiting effects on enzyme activity. Among inhibitory ions, the inhibition levels of Cu²⁺ and Ca²⁺ were strongest, with a 50% decrease in enzyme activity, thus proved to be the strongest inhibitors for this cellulase. Compared with wild strain CMC-4, the enzymatic properties and enzyme producing conditions for the mutant strain CMC4-3 changed partly, and showed more wide range of environment adaption. Thus a strain of Bacillus licheniformis with stable high-cellulase producing and wide adaption range was obtained. Moreover, the phenotypes of CMC-4 and CMC-4-3 could be the clue for studying genotype changes and the underlying molecular mechanism of mutation breeding.