Abstract: In order to biodegrade natural chitin, in this study, chitin was used as the sole carbon source, obtain chitin deacetylase strains which could produce chitosan from natural chitin by biological method. Results showed that, the strains were identified by color plate screening and enzyme activity rescreening, morphological characteristics and 16S rRNA sequence analysis. A bacterium X4 with higher activity of chitin deacetylase was obtained, and was identified as Lysinibacillus sp.. The fermentation culture of the strain showed that the activity of chitin deacetylase produced by X4 could reached 8.210 U/mL, and the deacetylation degree of chitin was 8.642%. The results was valuable for the green biological utilization of chitin.