Abstract: This paper studied the effect of combined application of boron, manganese, and molybdenum on grass yield and mineral element contents and yield of alfalfa by the method of leaf surface spurting. The result show that: different combined application all could improve the yield of alfalfa, among all the treatments the effect of single application Mo was the best, the follow was B and Mo combined application treatment, compared to CK, increase was 54.75%, 40.34%, respectively. Different B, Mn and Mo combined application has different influence on mineral element contents and accumulation amount of alfalfa. combined application micronutrient fertilizers decreased Fe, Mn and Zn contents, and B and Mo combined application has an obvious effect. But they could increase the Cu content of alfalfa, and the effect of B, Mn and Mo combined application was the best. B+Mn and B+Mo treatments could singificantly increaser B and Mo contents of alfalfa, respectively. Different combined application all could improve the mineral element accumulation amount of alfalfa. Single application of B could emarkably increase Fe, Mn and Zn accumulation amount, while single application of Mo and B, Mn and B, Mo combined application could significantly increase Cu, B and Mo accumulation amount of t alfalfa respectively.