In order to study the effects of organic manure application rate on soil enzyme activity and bacterial community in blacksoil，the correlation between the changes of bacterial community in black soil and the application rate of organic fertilizer wasdetermined，which provided a scientific basis for regulating soil microbial community structure and improving its ecological function.No application of organic fertilizer(CK)，organic fertilizer application of 15000(YJ1)，22500(YJ2)，30000(YJ3)，37 500(YJ4)and 45 000 kg/hm²(YJ5)were carried out through two consecutive years of field experiments to study the changes ofsoilinvertase，urease，catalase，alkaline phosphatase activity and bacterial communitydiversity.Application of organic fertilizerincreased soil invertase(26.3%～56.6%)，urease(5.8%～56.4%)，catalase(0%～17.7%)，alkaline phosphataseactivity(7.4%～43.6%)，and enzyme activity of YJ2 treatment was thehighest.The application of organic fertilizer improved therelative abundance of Proteobacteria and Firmicutes bacteria in blacksoil，and reduced the relative abundance ofActinobacteria.Catalase and invertase are the major factors that affect the diversity of bacterial communities.The application of organic fertilizercould increase the number and variety of bacteria in different degrees，and then the soil system develops in a stable and healthydirection.