The article defines the connotation and constructs the evaluation index of product quality upgrading, and reveals the influence mechanism of product quality upgrading on relative wage gap. Based on the perspective of enterprise heterogeneity, this article empirically tests the impact of product quality upgrading on relative wage gap by using the micro data of China's industrial enterprise database and customs database from 2000 to 2013. The research results show that: (1) Product quality

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... ng have a significant positive impact on the relative wage gap, and the impact of different levels of product quality upgrading on the relative wage gap is different. ( 2 ) Enterprise heterogeneity has a significant impact on the relative wage gap. Among them, the better the enterprise performance, the stronger the innovation ability, the higher the total factor productivity and capital intensity, the greater the export subsidies, the higher the degree of foreign participation and monopoly, and the bigger the relative wage gap. There is a large relative wage gap between export enterprises and in-system enterprises. On this basis, it puts forward some policy suggestions with certain reference value. The results of the article provide important policy implications.