Abstract: Based on the relevant data of 31 large and medium-sized cities in China from 2001 to 2018, the formation mechanism of rail transit consumption effect is discussed from the perspectives of economic growth and marginal consumption tendency. The impact of rail transit construction on urban consumption level is empirically analyzed by using multiperiod model of Differences-in-Differences(DID). The results show that rail transit construction may have a significant positive impact on urban consumption by promoting the growth of residents' income and improving the residents' marginal propensity to consume. The heterogeneity test results show that the consumption promotion effect of rail transit construction in the central-eastregions and big cities are more pronounced than the western regions.