Abstract: The report studied the effects of different fertilizer treatments on the growth of the 7th years-old of 3 different production performance alfalfa（Medicago sativa） varieties, as well as changes in soil nutrients. The results showed: NP combined application and K fertilization alone can significantly increase the yield of all different alfalfa varieties. Different fertilization shows different impact on the productivity of different varieties. When applied N30P120, the highest forage production was obtained for both Ameri Stand 201+Z and Ameri Graze 401+Z reached, increasing 41.1% and 74.8% more than that of non-fertilizer respectively. When applied K60, Lobo will gain the largest production increase (76.7%). Planting alfalfa can improve the soil N availability, and it is accumulated in soil that the nitrogen was firmed by roots of the 7th years-old alfalfa (sentence is not clear). The soil N content of non-fertilization increases with alfalfa planting, but total P、total K in soil decreased. The impacts of fertilization on soil fertility are different with different alfalfa varieties planting. The soil available P content increases with increases of P fertilization. Applying K alone can raise the soil available P content (3.71–4.41 mg/kg) and total K content (0.06–1.69 mg/kg).