Based on the 12 treatments of Chinese milk vetch （Astragalus sinicus L.）and straw returning under different levels of chemical fertilizer on field in Wuhan City,Hubei Province,combined with laboratory culture experiment of adding 2% and 4% Chinese milk vetch,the effects of Chinese milk vetch returning (MV),rice straw returning (S) and chemical fertilizer reduction (40%-100% NPK) on soil nutrient and active organic carbon in the surface layer (0-20 cm) of paddy soil were investigated. Compared with the control treatment of no MV,no S and non-fertilizing,the use of reduced chemical fertilizers with MV and S could effectively increase soil organic matter,alkali nitrogen and particulate organic carbon,which increased by 3.98%-46.49%,4.46%-35.88% and 3.59%-35.77%,respectively. The content of available phosphorus and potassium in the soil treated with MV only was significantly reduced,while it was significantly increased after S and chemical fertilizer treatments. The soil nutrient contents were the highest at treatment of 80% NPK. Adding 2% and 4% of Chinese milk vetch indoor culture could effectively improve the soil pH,organic matter,available nitrogen,available potassium and particulate organic carbon contents,and they were increased with the adding amount of Chinese milk vetch.