Abstract: As a core institutional guarante for developing a unified national market, the negative list system for market access is a key driver to deepen domestic intra-produet division of labor and build independent and controllable industrial and supply chains., Against the backdrop of building a unified national market, this paper explores the impact of market access refom on domestic intra-product division of laborand its underlying mechanisms. The results show that the negative list system for market access significanly depens domestie intra-productdivision of labor, Mechanism analysis reveals thal this syslem faciliales the two-way fow of factors on the supply side and expands marketcale on the demand side, thereby advancing the relinement of domestic intra-product division o labor, Heterogeneily analysis indicates thatthe negative list system strengthens the release of comparative advantages, promotes regional balanced development, and facilitates the organic integration of an efective market and a proactive govermment, namely, it exerts a more significant deepening eflect on domestic intra-product specialization in regions characterized by lower capital-labor raltios, higher levels of goverment inlervention, lower market vitality, as well as in central and westem China. This study clarifies the institutional efiects of market acces refomn on intra -product division of labor, Amid the profound restnucturing of global value chains, it also offers policy implications for empowering the development of a unified national market and fostering a moder industrial and supply chain system through institutional reforn and innovation in the market.
