Objective： A fungal with high activity of chitosanase was isolated from soil samples and named as M7a. Then， optimize solid fermentation conditions of the strain M7a for chitosanase production. Method： The strain M7a was identified based on its morphological characters and 18S rDNA sequence. The single factor and response surface test were used to determine it’s optimum solid fermentation conditions for chitosanase production. Result： The strain M7a was identified as Purpureocillium lilacinum. The optimum solid fermentation conditions were confirmed as follows： 10 g/L colloidal chitosan + 5 g/L glucose， 10 g/L peptone， the mass ratio of soybean meal was 7 ∶ 5， the initial pH of the medium was 6.0， 33 ℃ for 5.5 d. The final chitosanase activity reached 16.80 U/mL， which was 5.1 folds higher than the beginning after optimization. SDS-PAGE and zymography analysis showed that the strain M7a secreted a 40 ku chitosanase without isozyme. Conclusion： This study screened and identified a novel strain of Purpureocillium lilacinum M7a with high chitosanase activity， and greatly improved the chitosanase production level of solid fermentation. The results can provide a theoretical basis for purification and application of the chitosanase from Purpureocillium lilacinum.