Abstract: In order to explore the method of one time fertilization of rice, two conventional japonica rice cultivars Nanjing 9108 and Nanjing 5718 are used as test cultivars. Four different slow controlled release fertilizer and urea ratio treatments (T₁: 100% slow controlled release fertilizer, T₂: 70% slow controlled release fertilizer+30% urea, T₃: 50% slow controlled release fertilizer+50% urea, T₄: 30% slow controlled release fertilizer+70% urea) and conventional urea separate application treatment (CK) are set up to study the effects of different slow controlled release fertilizer and urea ratio applied as base fertilizers at one time on yield formation and nitrogen absorption and utilization of conventional japonica rice under the condition of 270 kg/hm² nitrogen application rate. The results show that the yield and total dry matter accumulation of the two test varieties are significantly higher than those of CK under T₃ treatment, while T₁ and T₄ treatments are significantly lower than CK treatment. The main reason that T₃ treatment can increase yield is that it has higher effective panicles per unit area and grain number per panicle. There is no significant difference in seed setting rate and 1 000-grain weight among different treatments. At jointing stage, the number of tillers in T₁ treatment