Abstract: An acidic chitinase from Streptomyces thermoviolaceus Z16 was purified and characterized in the present study. The enzyme was purified to homogeneity with a purification fold of 12. 7, and a recovery yield of 22. 3%, by two steps of ammonia sulfate precipitation and ion-exchange chromatography. The molecular mass of the purified enzyme was estimated to be 41. 6ku and 40. 8ku by SDS ~ PAGE and gel filtration, respectively, indicating that the enzyme was a monomer. The chitinase was an acidic enzyme since it was most active at pH4. 0, and remained relative high activity in pH3. 0 ~ 6. 0. The optimal temperature of the enzyme was determined to be 60℃. The enzyme was stable at 55℃ and 60℃, with thermal denaturing half lives of 267min and 132. 9min, respectively. The enzyme showed strict substrate specificity, it can efficiently hydrolyze colloidal chitin to release acetylglucosamine, chitobiose and small amount of chitotriose.