Through five years of positioning experiment，the effects of organic manure replacing chemical fertilizer on soil nutrients and enzyme activities were studied，and reducing fertilizer and increasing fertilizer efficiency was explored.Five different fertilization treatments were set up in the field experiment :(1) 100% chemical fertilizer nitrogen (CK)；(2) 25% organic manure nitrogen +75% chemical fertilizer nitrogen (M25)；(3) 50% organic manure nitrogen +50% chemical fertilizer nitrogen (M50)；(4) 75% organic manure nitrogen +25% chemical fertilizer nitrogen (M75)；(5) 100% organic manure nitrogen (M100).The results showed that:compared with CK，there was no significant difference in soil total nitrogen and alkali-hydrolyzable nitrogen content in 2019 (the fourth year of fertilization) and 2020 (the fifth year of fertilization) for organic manure replacement treatments，while there was no significant difference in total phosphorus content in 2019，but the total phosphorus content in 2020 in organic manure replacement treatments were lower than CK.M50，M75 and M100 treatments were 0.89，0.91 and 0.90 g/kg，significantly reduced by 17.87%，15.24% and 16.47%，respectively，compared with CK.M25 treatment had no significant difference compared with CK.In 2019 and 2020，soil available phosphorus content of M100 treatment was 31.03～36.37 mg/kg.Compared with CK，M100 treatment significantly increased soil available phosphorus content.In the experiment of 2020，the content of soil available phosphorus in each organic fertilizer replacement treatment group was significantly higher than that of CK.Compared with CK，there were no significant differences in soil urease activity and phosphatase activity in organic fertilizer replacement group.In the experiment，there were no significant differences in ear length，ear diameter，ear row number and grain number per row of organic manure replacement treatments compared with CK.However，the bald tip of organic manure replacement treatments were smaller than that of CK in 2020，M25，M50，M75 and M100 treatments were 28.57%，26.53%，14.29% and 24.49% less than CK，respectively.Compared with CK，the hundred grain weight of M75 and M100 treatments increased significantly by 10.14%～14.17% and 20.54%，respectively.Compared with the single application of chemical fertilizer，the replacement of organic manure with equal nitrogen amount could not reduce soil nutrient content (in addition to the total phosphorus content decreases) and soil enzyme activity，could increase to some extent the maize grain hundred grain weight，reduce bald tip length，but also could optimize ear traits of maize to a certain extent and reduce the application of chemical fertilizer.Therefore，the replacement of organic manure with equal nitrogen amount is a fertilization way of fertilizer saving，efficiency increasing and environment protecting.