This paper empirically investigates the mechanism through which product market competition (PMC) affects disclosure quality of listed companies. Based on a sample of listed companies with disclosure quality report from Shenzhen Stock Exchange during 2003–2008, PMC is found to display a U-shaped relationship with disclosure quality, which demonstrates the strategic effect of PMC on disclosure quality. PMC is also found to enhance the board of directors’ role in disclosure quality, which demonstrates the governance effect of PMC on disclosure quality. These results enhance the understanding of the role of PMC on disclosure.