Identifying the net effect and mechanism of reform and opening-up and poverty reduction miracle in China is the key to promoting economic high-quality development. The study constructs a dynamic structural model that includes reform and opening-up, consumption growth and residents' welfare, and for the first time adopts a synthetic control method to scientifically assess the impact and mechanism of reform and opening-up on consumption growth and adopts counterfactual simulation method to measure the welfare effect. This study finds that reform and opening-up has accelerated consumption growth rate by an average 5 percent every year since 1978, that the welfare enhancement brought about by it is equivalent to a permanent annual payment of RMB 3 446 yuan per person; and that it has contributed to the consumption growth through promoting the channel of income growth. Based on the welfare effect of consumption growth, the paper analyzes the great achievement in poverty reduction created by reform and opening-up, which serves as an vital inspiration for further deepening reform and opening-up and alleviating residents' inadequate consumption in the new journey.