Tariff Concessions, SPS Barriers and Agricultural Trade Efficiency Between China and Vietnam: Evidence from Multi-product Stochastic Frontier Gravity Model

Against the backdrop of deepening RCEP regional economic integration and continuous upgrading of China-Vietnam bilateral economic and trade cooperation, agricultural trade, as a core component of cross-border commodity trade between the two countries, plays a vital role in optimizing bilateral trade structures and promoting regional industrial complementarity. In recent years, continuous tariff concession policies have significantly reduced the tariff cost threshold for China-Vietnam agricultural trade, while sanitary and phytosanitary (SPS) barriers, as typical non-tariff trade barriers, have gradually become the core restrictive factor affecting bilateral agricultural trade flows and efficiency. Existing studies mostly adopt traditional gravity models to analyze the linear correlation between trade policies and trade volume, lacking targeted efficiency measurement and heterogeneous mechanism analysis of multi-category agricultural products. Based on panel data of 28 subdivided agricultural product categories traded between China and Vietnam from 2015 to 2024, this study constructs a multi-product stochastic frontier gravity model to measure the overall efficiency and loss level of bilateral agricultural trade, and systematically explores the differential impact of tariff concessions and SPS barriers on agricultural trade efficiency. Further, this paper conducts heterogeneous subsample tests based on product attributes including primary agricultural products, processed agricultural products, and tropical characteristic agricultural products. The empirical results show that tariff concessions significantly improve China-Vietnam agricultural trade efficiency and reduce trade inefficiency loss, while SPS barriers produce prominent inhibitory effects on trade efficiency; the two factors present significant interactive offset effects in bilateral agricultural trade. Heterogeneous test results indicate that primary agricultural products are most sensitive to SPS barrier restrictions, processed agricultural products benefit the most from tariff concession dividends, and tropical characteristic agricultural products have the lowest overall trade efficiency due to dual constraints of high compliance costs and strict technical standards. Regional economic cooperation mechanisms, border infrastructure construction and institutional trade openness can significantly alleviate trade efficiency losses caused by SPS barriers and amplify the positive effect of tariff concessions. This study clarifies the hierarchical influence mechanism and heterogeneous action logic of tariff and non-tariff barriers on China-Vietnam agricultural trade efficiency, fills the research gap of multi-product differentiated empirical analysis in bilateral agricultural trade research, and provides empirical evidence and targeted policy references for optimizing China-Vietnam agricultural trade layout, breaking through technical trade barriers, and improving bilateral agricultural trade facilitation and efficiency under the RCEP framework.