Development of a national unified grand market is a cornerstone and an inherent demand of our country’s new development paradigm, and the tax system will play an important role in this process.A perfect tax system is conducive to the development of a national unified market.However,there are still some problems in China''s tax system, such as lack of regulations for regional preferential tax policies, poor results from preferential tax policies for scientific and technological innovation, and prominent deviation between tax revenue and tax sources,which have seriously restrict the development of a national unified market.So it is necessary to regulate regional preferential tax policies,to ensure the implementation of the preferential tax policies of science and technology innovation,and to constantly perfect the unified tax system,so as to contribute to the development of a unified grand market and further promote the quality development of our economy.