Soil microflora,soil enzyme activity and soil biochemical function were studied under different types of vegetation and analyzed the changes of soil microbial activities during the process of forest succession in Maolan Karst Nature Reserve,in Guizhou Province.The results showed that,along with Karst forest degradation being intensified,the total population of major soil microbes was declining;the numbers of major physiological groups,including ammonifiers,cellulose decomposing microbes,nitrogen fixing bacteria were decreasing;the activity of soil enzymes,including urease,sucrase,proteinase,alkaline phosphatase,peroxidase,and polyphenol oxidase were weakening;soil biochemical functions,including ammonification,nitrification,nitrogen fixation and cellulose decomposition were being impaired.Soil microbes activities were sensit ive to the process of forest degradation and could be deemed as microbial indicators of Karst forest ecology system.Soil microbes and enzyme activity were recommended as one of the major characteristics of ecological functions of Karst forest.