The construction of a unified national market is an inevitable requirement for the implementation of a socialist market economy, and the realization of a positive interaction between an effective market and responsible government requires the application of the rule of law to get rid of the adverse effects caused by local protectionism and market monopoly division on the flow of resources. Since the 14th National Congress of the Communist Party of China decided to establish a socialist market economic system, the idea of “a unified national market” has been mentioned for many times. However in practice, a series of such policies often have little effect. The lack of a constitutional understanding and handling on the relationship between the central and the local governments is one of the main reasons for the difficulties in constructing the unified market. Therefore, in order to implement the policy of unifying the large market, it’s necessary to dig deeper into the constitutional implications of the policy, carefully analyze the de jure or de facto constitutional issues in the process of implementing the policy, and provide the fundamental legal safeguard for the “unified national market”.