Differential Game Analysis of Cross-Border E-Commerce Supply Chains Under Dual Trade Barriers

This study examines a two-echelon cross-border e-commerce (CBEC) supply chain under the joint constraints of technical barriers to trade (TBTs) and tariffs. To capture the cumulative nature of foreign-market access, the degree of trade barrier breakthrough is modeled as a continuous-time state that converts technological innovation and compliance updating into sustained market access. A differential game is developed to compare centralized, decentralized, and modified two-part tariff contract decisions. The main conclusions are as follows: (1) Decentralized decision-making causes insufficient technological innovation and compliance updating, reducing the steady-state breakthrough level and total supply chain profit. (2) The modified two-part tariff contract internalizes the benefit–cost mismatch between the manufacturer and the retailer, reproducing the centralized investment path and total profit. (3) Government support strengthens barrier-breaking incentives, while the effect of tariffs on decentralized investment depends on the balance between subsidy support and upstream tariff pass-through; tariffs nevertheless reduce the integrated channel margin and may invalidate the contract beyond a critical threshold. (4) Product-life-cycle analysis shows that technological innovation dominates during technology dividend periods, while compliance updating becomes more valuable during bottleneck periods. (5) Multi-scenario simulations and ±20% one-factor perturbations preserve the ranking C = MT > D. These findings extend dynamic supply chain coordination research by linking investment, realized market access, and contract incentives under dual trade barriers, and provide implications for the long-term economic sustainability of CBEC supply chains.