The socialist market economy system reform with Chinese characteristics is one of the most important contents in China’s economic reform practice. From the reality of China’s economic development, the transformation of macroeconomic policies, and the academic discussion in the theoretical circles, it can be concluded that China’s market economy system reform entered the deepening exploration period since 2012, and it is urgent to change the economic growth mode to a higher quality socialist market economy with Chinese characteristics. This paper systematically studies the thought trajectory, policy practice and performance analysis of the socialist market economy system reform with Chinese characteristics entering the deepening exploration stage since 2012.

At the thought level, China’s market economy system reform has achieved the multi-dimensional innovation and development since 2012. Among them, the basic understanding of the economic" New Normal” is the era background and the thought premise of China’s deepening market economic reform. The proposal of " New Development Concept” is its main line of thoughts and overall guidance of China’s deepening market economic reform, while the conception of " Modern Economic System” and the initiation of" Community with Shared Future for Mankind” are the thought expansion and extension respectively in internal direction and external direction. The thought trajectory of China’s market economy system reform’s deepening exploration is developing along this thought premise, the overall guidance, and the thought expansion in internal direction and external direction. These new ideas not only have theoretical breakthroughs and innovations in answering important questions such as " what kind of development we want and how to achieve it”, " what kind of world we want and how to achieve it”, but also provide an ideological and theoretical basis for China to deepen the practical practice of the market economy system reform.

At the level of practices, based on the evolution of China’s reform thinking since 2012, the key policy practices for deepening reform in this period can be elaborated from two sides: one is the construction of " six systems, one organization” guided by the concept of " Modern Economic System”; the other is the construction of the " Belt and Road” under the guidance of the " community of human destiny”. These policy practices are the realistic manifestation of thought evolution, and at the same time provide a practical source for thoughts’ further development and innovation. The dynamic interaction between the two aspects promotes the deepening development of the socialist market economy system reform with Chinese characteristics, which has made remarkable realistic achievements in the economic structure, urban and rural regional development, people’s living standards, ecological civilization construction, and new international economic relations.

Since the deepening exploration period of the market economy system reform in 2012, the organic combination and effective interaction between China’s reform thoughts and policy practices is not only the realistic embodiment of the basic logic of historical materialism of Marx’s " social existence determines social consciousness, social consciousness counteracts social existence”, but also one of the most important experiences of China’s success in the socialist market economic reform since the founding of the People’s Republic of China. It is further one of the most important principles that must be adhered to cope with the current severe domestic and international challenges and to promote the construction of a more mature socialist market economy with Chinese characteristics.