Based on macroeconomic data of Shanghai in the first three quarters of 2020 and before that，we analyze current and past economic situation of Shanghai，and predict the economic growth of Shanghai in the next year under different scenarios by combining with the input-output model. It is estimated that under the optimistic scenario，there is a rebound in the first half of 2021，with the growth rate exceeding that of 2019. It shows a trend of high growth then low growth，and the annual GDP growth rate is expected to reach 6%. Under normal circumstances，Shanghai’s economy in 2021 will be slightly higher than the growth level in the second half of 2020，and the annual GDP growth rate will remain around 4.5%. Under the pessimistic scenario，it is estimated that the first half of 2021 will barely remain at the level of the second half of 2020，and the second half will continue to decline，with annual GDP growth at around 3%.