Abstract: To study the effect of fertilization on the production of alfalfa, takingMedicago sativa L. cv.‘Xinmu No.4’as the material, the 3414 fertilization experiment was conducted, and the effects of different nitrogen, phosphorus and potassium proportional fertilization on the yield and quality of alfalfa were studied. The results showed that the different fertilization treatments had different effects on yield and quality of alfalfa. The fresh yield of N2P2K3 was the highest (83.62 t/hm2), and that of N2P2K1 was the second, they increased by 28.31% and 20.42%, respectively, compared with N0P0K0 (65.17 t/hm2). The crude protein content of the first cutting was the highest in the leaves and stems of each treatment. The content of leaf protein in each treatment was higher than that of the stem, but the acid washing fiber and neutral detergent fiber were lower than that of the stem. The leaf protein of N2P2K0 was the highest in the first cutting, which was 30.94%. The average leaf protein content of N1P2K2 was the highest in the three cuttings, which was 28.44%, and the N2P1K2 was the second, N2P2K2 was the lowest, which was only 23.00%. The comprehensive analysis shows that the optimum ratio of fertilization for 2-year-old alfalfa in the experimental area is N2P2K3 combination, 120 kg/hm2 urea + 90 kg/hm2 superphosphate +90 kg/hm2 potassium sulfate.