Abstract: Effects of microbial fertilizer on the soil ecosystem and growth of cotton were studied.The results show that microbial fertilizer,used alone or mixed with other organic fertilizers,can increase the total microbial biomass and improve the soil fertility.At the same time the unit weight of soil is decreased,and the cation exchange capacity,available P,alkaline hydrolysis N,and available K are increased.When microbial fertilizer is used alone,the yield of cotton increases by 19.2%,and when it is used together with organic fertilizers,the yield increases by 31.6% than CK.The efficiency of microbial fertilizer mixed with other organic fertilizers is better than that used alone.