A strain producing the cold-adapted protease has been isolated from the frozen soil of the Tianshan Mountains,China.Based on the morphological,physiological,biochemical properties and 16S rDNA sequence analysis,the strain was identified as Pseudomonas sp.N-8.Fermentation conditions were optimized by single factor and orthogonal experiments.The optimal medium components were determined as follows:10 g/L glucose,8 g/L yeast powder,20 g/L casein,0.4 g/L KH2PO4,pH 7.0.The research on the properties of crude enzyme showed that the optimal pH and temperature for activity were 7.0 and 25 ℃,respectively.As to the thermal stability of the cold-adapted protease,it was stable over the range of 25～45 ℃.The test of pH stability indicated that the cold-adapted protease was more stable within pH 7.0～8.0.The protease activity was inhibited by Cu2+,K+,Ca2+,and Mn2+,but it was stimulated by Fe2+,Mg2+,Na+,and Zn2+.