Abstract: To address the order-splitting problem for cross-border e-commerce (CBEC) in multi-item orders, this study proposes an optimization strategy incorporating customer satisfaction to reduce logistics costs from repeated deliveries and improve delivery timeliness. Through numerical analysis, two strategies are examined for multi-item orders: distance-priority allocation and flexible allocation. Optimization models are developed to minimize total fulfillment costs and maximize customer satisfaction, solved by NSGA-II and INSGA-II. Experimental results show that: 1) the adaptive INSGA-II significantly improves solution efficiency compared with NSGA-II; 2) compared with the distance-priority allocation strategy, the flexible allocation strategy enhances service quality with moderate cost increase, yielding superior overall benefits; and 3) sensitivity analysis verifies the robustness of flexible allocation under varying parameter settings. These findings provide effective insights for CBEC in order-splitting optimization.