Abstract: [Objective] In this study, the control effects of mixed planting of spring wheat and alfalfa on the occurrence rate of weeds in fields were investigated and made clear, and also the effects of conservation tillage on the yield and nutrient quality of alfalfa of the first cut were discussed.[Method]Spring wheat seeding rate gradients included 120 kg/hm2 (S1), 80 kg/hm2 (S2), 240 kg/hm2 (S3), respectively, and alfalfa without sowing was taken as the control (S0).The growth characters of the first cut alfalfa were determined and analyzed.[Result]With the increase of sowing amount, the dry matter yield of spring wheat increased gradually, and the proportion of weeds decreased from 35.3; to 18.4;.The height, stem diameter, stem leaf ratio, hay yield of first cut alfalfa was S1>S0>S2>S3, and the S1 treatment yield was significantly higher than those of S3 and S0 (P<0.05), and there were no significant differences between the treatments S1and S2, S2 and S3, S0 (P>0.05) in the year of sowing.The crude protein, neutral detergent fiber, acid detergent fiber, ether extract, calcium and phosphorus content in the first cut alfalfa gradually decreased, and the S1 treatment was significantly higher than the S0 and S3 treatment (P<0.05), and the two alfalfa varieties showed the same variation rule.[Conclusion]Protectiive sowing can effectively reduce the proportion of weeds in alfalfa fields.Considering the yield and nutritional quality of alfalfa, the best performance of the first crop of alfalfa can be obtained when the sowing amount of spring wheat is 120~180 kg/hm2.