In the context of climate change, extreme precipitation is increasing gradually with the increase of urban rain island effect. In this paper, the Shanghai Urban flooding assessment Model (SUM) is used to analyze the urban flooding vulnerability characteristics in different drainage blocks. On the basis of the future rainfall intensity simulation, urban flooding scenarios in the downtown are established to analyze the influence of climate change on urban drainage. This paper also makes an assessment of urban flooding adaptability in Shanghai in the context of climate change of RCP45 and RCP85 The results indicate that the urban flooding vulnerability in the districts of Jing’an, Huangpu, Hongkou, and Changning is relatively higher than that in other areas. Under climate change, the urban flooding will be strengthened gradually. Taking the precipitation recurrence period of once every three years as an example, the increase of flooded area in the central area is about 374 km2/10a. Under the current drainage capacity, the average growth of 1486% per decade of the pervious area for various drainage blocks can offset the strength of urban flooding caused by climate change, and the expected increase of the pervious area in Pudong will be lower than that in Puxi.