This paper first describes the achievements of China's opening-up, and then compares them with China's domestic trade development. It is pointed out that due to the great differences in natural climate, economic development degree and customs among regions, a unified market in the true sense has not been formed, which leads to the practical problems that the cross regional development of enterprises is blocked, and then highlights the importance of building a unified national market. Finally, suggestions are put forward for the construction of the unified national market from the following four aspects:
1. Break down local protection and regional barriers and expand opening up to the domestic market
2. Strengthen basic market system and unify competition rules
3. Follow the steps of gradual reform from easy to difficult
4. Effectively reduce the cost of the masses and the burden of government management
