ABSTRACT This article investigates how intermediaries’ imported inputs affect nondirect import firms’ product quality. Based on WIOD input‒output tables and microlevel China customs trade data, the result shows that intermediaries can significantly improve nondirect import firms’ export quality mainly through imported quality rather than imported quantity. In addition, the promotion effect of intermediaries’ import quality is greater for nondirect import firms with a larger scale, higher export intensity and longer export year; the imported quality of ordinary intermediaries has a greater effect than that of professional intermediaries. Furthermore, the imported quality of intermediaries is also conducive to alleviating the negative effect of the quality directly imported by peer firms in the same industry. This study not only explores intermediaries’ supporting role in the supply chain but also puts forward some policy implications of export product quality upgrading for SMEs.