Abstract: Industrial policy is an important way for the government to regulate the macroeconomy and play its role. Accurately grasping the intensity and direction of policy implementation should be the key issue for giving full play to the effective market and the effective government and promoting the construction of a unified national market. However, existing studies have not given targeted conclusions and inspirations. In this regard, this paper explores the impact of regional industrial policy implementation on domestic market segmentation based on theoretical analysis and empirical tests. The results show that the implementation of regional industrial policies helps to alleviate the degree of domestic market segmentation as a whole, but there is a threshold effect in the specific implementation process. Therefore, in order to better play the role of industrial policies, it is necessary to pay attention to the "moderate range" of policy implementation intensity. Heterogeneity analysis found that there are significant differences in the "moderate range" in regions with different government governance capabilities and economic development levels, which means that the above factors should be fully considered when optimizing the positive benefits of industrial policies on the construction of a unified national market. This provides an important reference for the implementation of industrial policies at the central and local levels to help the construction of a unified national market.

Key words: national unified market, industrial policy, market segmentation, threshold effect, moderate interval