Investigations were conducted on dynamics of grain yields and nutrients uptake of rice,and ecological characteristics of soil microorganisms in a paddy field under long-term fertilization experiment,which was designed to have five fertilization treatments,CK(control),PK,NK,NP,and NPK,and two crop treatments,conventional rice and hybrid rice.The results show that grain yield of rice was positively correlated with the total uptakes of N,P and K,and the soil available nutrient pool depleted rapidly under consecutive cropping without fertilization.The results also show that balanced N,P and K application improved functional diversity of soil microbes and increased total microbial biomass of the soil.Unbalanced fertilization decreased microbial N but increased C/N ratio of the soil microbial biomass.It is found that soil nutrient deficiency and unbalanced fertilization to rice crops have a negative effect on diversity of microbial communit ies and total microbial biomass in the soil.