Abstract: At present, chitosanase used to prepare chito-oligosaccharides has the disadvantage of low enzyme activity and poor acid stability. In this study, chitosanase-producing strain was screened from mud samples from Lianyungang Haizhou Bay, the highest chitosanase-producing strain was identified, and the acid stability and enzyme properties of the strain were studied. The screening was carried out by using the transparent zone method, and shaking flask fermentation. The chitosanase producing strain CLT08 was obtained. Then, the strain CLT08 was identified as Paenibacillus chitinolyticus with morphological characteristics, physiological and biochemical determination and 16S rDNA sequence amplification and analysis. The optimum temperature and pH for chitosanase production of strain CLT08 were 45 ℃ and pH4.0; Zn²⁺ had a significant activation effect on the enzyme, and Ba²⁺, Co²⁺, Fe²⁺ had significant effects inhibition. The degree of polymerization of chitosan was≥6 after being hydrolyzed by CLT08 chitosanase. The results of this study laid the foundation for further research on the enzyme.