In this article effects of different proportions of manure and chemical fertilizer on soil nutrition,enzyme activity and crop yield were studied in a fouryear experiment.The results indicated that the treatments 0.3M(70% chemical fertilizer +3 000 kg/hm2 manure) and 0.5M(50% chemical fertilizer +6 000 kg/hm2 manure) had a higher level of total N,available P and available K than NPK treatment(only chemical fertilizer),and in 0.5M treatment was higher than those of 0.3M treatment(P<005),which indicated that higher proportion of organic manure lead to higher soil nutrient.The order of soil urease activity was NPK＞0.3 M＞0.5 M＞CK.For soil invertase activity and catalase activity the order was 0.5 M＞0.3 M＞NPK.The total wheat yield of 0.3M treatment was 5.95% higher than that of NPK treatment,but that of 0.5M treatment was 0.94% lower than that of NPK treatment(P<0.01).The total maize yield of 0.3 M treatment was 1.27% lower than that of NPK treatment,while that of 0.5 M treatment was 2.00% lower than that of NPK treatment(P<0.05).These results confirmed that manure supplement 30% chemical fertilizer had a high yield in a low chemical fertilizer level,manure supplement 50% chemical fertilizer effectively conserved soil fertility.