Abstract: Objective and MethodThe studies were carried out on the effects of 5, 10, 15 and 20 years continuous cropping cotton soil on the microbial quantities, activities and enzyme activities in Xinjiang.ResultThe results showed that continuous cotton cropping has great effect on the number of its soil microbes and soil enzyme activities. With increasing year of cropping, the amount of bacteria, actinomycetes and fungi had a slight decrease. The amount of bacteria in the soil microorganisms proves to have the absolute superiority over actinomycosis and fungi. With increasing year of cropping, the B/F had a slight decrease. ConclusionThe soil urease, phosphatase,invertase of cotton field with different cropping years were determined.The results demonstrated that the change of urease and invertase were similar to one another,which was increased with the increasing of continuous cropping years,but the activity of phosphatase was decreased first,then was increased with the increasing of continuous cropping years.