Field experiment was carried out to study the applied amounts of N, P, K fertilizers on the yields and nutrient accumulations of green manure in order to decide the optimal fertilizer amounts in the condition of rice-Chinese milk vetch rotation system. The results showed that the fresh grass yields with N, P, K fertilizer treatments increased by 27.9% - 40.9%, 12.6% - 37.2% and 21.4% - 46.2% than no N, P, K fertilizer treatments respectively. Among N fertilizer treatments, N accumulation of the treatments with N fertilizer increased by 48.8% - 62.3% than no N applied, C, N, K accumulation reached to the maximal values with 142.4 kg/hm2 N fertilizer applied, P accumulation reached to the maximal value with 71.2 kg/hm2 N fertilizer applied. Among P fertilizer treatments, P accumulation of the treatments with P fertilizer increased by 33.0% - 78.3% than no P treatments, C, N, P, K accumulations reached the maximal values with 49.1 kg/hm2 P fertilizer applied. K accumulation of the treatments with K fertilizer increased by 22.2% - 44.8% than no K treatments, among K fertilizer treatments, C, N, P, K accumulations reached the maximal values when K fertilizer amount were 67.5 and 101.2 kg/hm2 in the rice season, and those two treatments had little difference. Under this experiment condition, the yield and C, N, P, K accumulations of green manure were 15 833 and 929.2, 44.6, 5.8 and 45.9 kg/hm2 respectively, while N, P, K fertilizer amounts were 142.4, 49.1 and 67.5 (or 101.2) kg/hm2 in the rice season.