A pot experiment of wheat-rice rotation was conducted to investigate the effect of controlled-release fertilizer (CRF)combined withurea(UR)on the soil biological characteristics.Dynamic changes of soil microorganism andenzyme activity in rice and wheat season were measured in seven fertilizationtreatments,including nofertilization,routinefertilization,10%CRF+90%UR,20%CRF+80%UR,40%CRF+60%UR,80%CRF+20%UR,and 100%CRF,whichrecorded as CK,T1,T2,T3,T4,T5 and T6,respectively.The results showed that the number of bacteria and actinomycetes in T4 treatment was significantly higher than that in T1 treatment with 30.22%～44.12%(wheat season) and 13.98%～66.96%(rice season),respectively,the amount of fungi were the highest in treatments of 20%～ 80%CRF,in jointing to mature stage of rice andwheat.The amount of soilammonifiers,nitrifiers and denitrifiers were thehighest in T1 treatment during tilleringstage.However,after jointingstage,the amount of soil ammonifiers and nitrifierswere the highest in treatments of 40% or above CRF while the denitrifying bacterias were the most with 80%～ 100%CRF.During jointing to maturestage,the treatments of 40% or above CRF increased the activities of soil urease andprotease,inparticular,the T4 treatment was the highest.The activity of soil protease showed significant correlation with bacteria andfungi in wheatseason,but there was no correlation in riceseason.The soil enzyme activity showed significant or extremelysignificant correlations with soilammonifiers,nitrifiers anddenitrifiers.Inconclusion,blending properly controlled-releasenitrogen fertilizer(the treatments of 20%～ 80%CRF)effectively increased the amount ofbacteria,actinomycetes,fungiand bacteria participating in nitrogentransformation,and enhanced activities of urease and protease during the mid-lategrowing stages of wheat andrice.Therefore,the biological characteristics of soil wereimproved,and soil nutrient releasewaspromoted,among which 40% CRF was the best treatment.