Abstract: Based on the criterion of " having a great impact on the existing economic theories (falsification or re-recognition), and having a great impact on China or the reality of the world economy”, this paper holds that since China’s reform and opening-up, the great contributions Chinese economists have made to economic science are that they proposed and have demonstrated " three important theoretical hypotheses”: Firstly, the unity or combination of socialist public ownership and market economic system. The second is the hypothesis of gradual transition of economic system, and the third is the hypothesis of " separating rural land ownership rights, contract rights and management rights”. This paper also explains why these " three hypotheses” are important economic theory innovations.