Abstract: By making use of the WITS tariff database and the BACI micro trade database and applying the theoretical model of import product quality frontier distance, this paper studies the impact mechanism of the tariff rate policy and the import product quality frontier distance on the export product quality based on the calculation of the export product quality upgrading standardization index of China's digital industry. By constructing the dynamic panel data model of systematic generalized moment estimation at the micro level, the results of the empirical study show that the quality of China's export products presents an upward trend, which is driven by the adjustment of the trade policy and the narrowing of the frontier distance of import product quality. The reduction of the tariff rate has a great policy impact on the price fluctuation of unit products, which has a further cross impact on the frontier distance of the imported product quality, resulting in the realization of the upgrading of export product quality. The results of the heterogeneity analysis show that the policy effects of the high-quality and low-quality frontier products, the high-tariff and low-tariff products and the products of different digital industries are quite different.

Key words: trade policy, quality of export products, quality frontier distance, system-GMM estimation