To improve the capacity of soil and water conservation and productivity of the gentle slope land in Mountain Area of Southern Ningxia,the research was studied on the effects of on soil moisture,nutrients,and crop yield on slope land in mountain area of southern Ningxia under corn-sainfoin intercropping.The experiment consisted of 5 treatments:whole corn （H₁）,whole sainfoin （H₂）,2 m corn+6 m sainfoin (H₃,H_3-C+H_3-S),4 m corn+4 m sainfoin(H₄,H_4-C+H_4-S),6 m corn+2 m sainfoin (H₅,H_5-C+H_5-S).The results showed that,the corn-sainfoin intercropping belt shows a good water balance utilization relationship,with H₄as the best balance point.In 0-20 cm,20-40 cm,60-80 cm soil.The lowest difference of soil moisture content between corn and sainfoin respectively are 0.4%,0.16%and 0.36%under H_4-Cand H_4-S.The content of sand in the 0-20 cm soil of the sainfoin planting treatment was reduced,and the effect of each treatment on the mechanical composition of the bottom layer of 20-40 cm soil was not significantly.The effect of different bandwidth on the change of organic matter content was as follows:as the bandwidth of corn increased,it increased firstly and then decreased;as the bandwidth of sainfoin grass decreased,it decreased firstly and then increased,with H₄being the turning point.Compared with H₁,H₃,H₄and H₅both improved the yield,which increased yield by 5%,16%and 22%,respectively.Compared with H₂,H₃and H₄increased the dry weight of sainfoin grass respectively by 32%and 23%,while the amount of H₅decreased.Overall,H₄is the optimal bandwidth to achieve maximum ecological economic benefits.