Based on four consecutive years of field experiment including the following 6 treatments:1) Winter fallow + N, P, K (CF); 2) Winter fallow + low amount of rice straw returning + N, P, K (RSL); 3) Winter fallow + high amount of rice straw returning+ N, P, K (RSH); 4) Chinese milk vetch + N, P, K (MV); 5) Chinese milk vetch + low amount of rice straw returning + N, P, K (MV+RSL); 6) Chinese milk vetch + high amount of rice straw returning + N, P, K (MV+RSH), this study comparatively analyzed rice yield, soil integrated fertility (IFI) and plant nutrients under the above treatments. In early rice season, rice yield remained stable when the organic substitution ratio was kept within 20% but significantly decreased when the substitution ratio reached 39%. In late rice season, compared with the CF treatment, organic matter returned significantly increased soil organic matter and total nitrogen contents, among which RSH treatment had the most significant effect, increased by 11.15% and 7.64%, respectively. Different proportions of Chinese milk vetch and straw replacing chemical fertilizers improved soil IFI, IFI of MV+RSH treatment increased by 8.5% compared with RSH treatment, and the treatments including MV or RSH significantly increased rice phosphorus and potassium contents compared with CF treatment. In conclusion, under the equal nutrient inputs, using 2 500 kg/hm² rice straw replacing 20% chemical fertilizers could ensure stable rice yield and increase soil fertility. The co-utilization of Chinese milk vetch and rice straw significantly increased soil fertility, however, the over-representation of organic substitution may result in diminished output in a short time.