Abstract:[Objective] Effects of straw returning coupled with application of the mixture of controlled-release urea(CRU) and common urea on maize yield and soil fertility were investigated, in an attempt to provide a scientific basis for rationalizing the application.[Method] A long-term field experiment from 2014 to 2018 was conducted to investigate effects of application of the mixture fertilizer consisting of sulfur and polymer-coated urea, polymer coated urea, and normal urea at a ratio of 3.5:3.5:3 in terms of N to summer maize (Zea mays L., Zhengdan 958) on yield. The experiment was designed to have six treatments:1) No nitrogen applied or straw returning (CK1); 2) No nitrogen applied in addition to straw returning (CK2); 3) Common urea applied only (BBF1); 4) Common urea applied in addition to straw returning(BBF2); 5) Application of the mixture only (CRF1); and 6) Mixture applied in addition to straw returning (CRF2). At the mature stage, soil samples were collected from the 0-20 cm soil layer of each plot for analysis, and LAI, SPAD, yield and yield composition of the maize were measured.[Result] Results show that:1) Treatment BBF2 was 5.9% and 13.3% higher than Treatment BBF1 in 5-year mean of grain yield and accumulative N use efficiency (ANUE), respectively, and Treatment CRF2 and CRF1 was 12.0% and 4.2% higher in maize yield, and 57.3% and 42.4% higher in accumulative N use efficiency, respectively, than Treatment BBF2; 2) The soil samples collected from Treatments CRF2、BBF2、CRF1 and BBF1 at the maize harvest stage in 2018 were 33.5%, 25.9%, 19.5% and 11.4%, respectively, higher in soil organic matter content, 26.6%, 18.6%, 9.9% and 7.0%, respectively, higher in soil total nitrogen content than their respective samples collected in 2013; 3) Treatment CRF2 and BBF2 was 11.8% and 13.0% higher in soil organic matter content, 15.2% and 10.9%, higher in total nitrogen content, respectively, than Treatment CRF1 and BBF1; 4) Treatment CRF1 was 52.0%, 18.6%, 19.5% and 24.7% higher in soil NO3--N, NH4+-N, available phosphorus and available potassium content, respectively, than Treatment BBF1, indicating that straw returning further increased soil nutrient content. Treatment CRF2 was 66.3%, 25.2%, 47.5% and 30.4%, higher, respectively, in soil NO3--N, NH4+-N, available phosphorus and available potassium content than Treatment BBF1.[Conclusion] All the findings demonstrate that long-term application of the mixture of urea fertilizers coupled with straw returning can significantly improve maize yield, ANUE, net income and soil fertility due to their synergistic interactions.