Appropriately selected best management practices (BMPs) may be highly effective to control soil erosion. However, the environmental efficacy and economic benefit of one or a combination of BMPs in reducing sediment loads remains an open question in arid and semiarid watersheds. This study employs the widely used Soil and Water Assessment Tool (SWAT) model, the multiattribute decision-making method, and the cost-effectiveness analysis method to simulate runoff and sediment and compares the environmental and cost benefits of 44 types of single and combined BMPs at both subbasin and basin scales. The main results are as follows: (1) the SWAT model performs well in the simulation of monthly runoff and sediment in the Yanhe River watershed, meeting the accuracy requirements for model calibration, validation, and application [runoff R2>0.66 and Nash-Sutcliffe efficiency (NSE)>0.64; sediment R2>0.6 and NSE>0.51]; (2) the sediment reduction rate of returning farmland to forestland + residue cover tillage + grass waterways was 41.73%, which was the best combination in terms of environmental efficacy; the cost-effectiveness (CE) value of grass waterways was far higher than that of other measures, which was 10,864.08 kg/& YEN;; and (3) the comprehensive attribute value Z of combined BMPs was better than that of single BMPs, and the grassed waterways + strip tillage (GW+ST) showed the highest Z value of 0.92 among all BMPs. These results help provide policymakers with authentic, effective, and tailored decision-making plans of soil conservation practices. DOI:10.1061/JHYEFF.HEENG-6221.(c) 2025American Society of Civil Engineers.