Through the method of fixed-point sampling,changes of microbial strains,microbial biomass carbon and five enzymes activities in greenhouse soil with different years cropping were evaluated.The results showed :(1) Changes of seasonal microbial strains were imcompatible with seasons in different years greenhouse cropping.The amount of bacteria increased firstly and then decreased,the highest amount appeared in June,while December was the lowest.The hightest amounts of actinomyces and fungi were in March,then declined gradually with seasons.The amount of microorganism became higher with years,while the percent of actinomyces and fungi to that one were lower.Compared with open field,the amount of fungi were incread more faster than bacteria in greenhouse cropping.(2) The hightest contents Of microbial biomass carbon occurred in March and June,and incread with different years greenhouse cropping.(3)Changes of seasonal soil enzyme activities were obviously with seasons in different years greenhouse cropping.Except catalase,the maximum enzyme activities of urease,acid phosphatase,neutral phosphatase and invertase occurred in March,the total enzyme activities were declined with years.