Abstract: In order to study the technical measures of high yield and quality of alfalfa in Hetao area,the effects of different application of boron,zinc and molybdenum on the yield and quality of alfalfa were studied on the basis of using phosphorus and potassium fertilizers.The results showed that reasonable application of boron,molybdenum and zinc can increase the yield of alfalfa on the basis of using proper amount of N,P and K fertilizers,and single application of boron or zinc can significantly increase the yield（P 0.01）.Application of boron 2 treatment increase the yield by 43.15% for the first stubble and 25.48% for the second stubble and total yield increased by 31.99% as compared to the control treatment.Application of zinc 3 treatment increase the yield by 36.77% for the first stubble,28.59% for the second stubble and total yield increased by 31.70%.Application of molybdenum 3 treatment increase the crude protein content by2.67 percentage points for the first stubble,2.78 percentage points for the second stubble and 1.01 percentage points for the third stubble as compared with the control treatment,application of molybdenum or zinc have significantly effects improving the quality of alfalfa（P〈0.05）.The crude fat content increased by 1.39 percentage points for the first stubble,1.25 percentage points for the second stubble and 0.48 percentage points for the third stubble.Application of zinc 3 treatment can increase crude protein content by 2.34 percentage points for the first stubble,2.39 percentage points for the second stubble and 0.94 percentage points for the third stubble and crude fat content increased by 1.30 percentage points for the first stubble,1.04 percentage points for the second stubble,0.32 percentage points for the third stubble.