With the climate warming, the frequency and intensity of disasters continue to increase. Effective disaster prevention and disaster emergency management requires a comprehensive understanding of the impact of disasters on the economy. The Dynamic Computable General Equilibrium Model (DCGE) was introduced into the disaster comprehensive economic loss assessment. Taking the rainstorms and floods in China from 2008 to 2016 as an example, the DCGE model in the disaster situation was constructed to measure the impact of the entire economic system. The empirical results show that: from the perspective of the current period, the occurrence of rainstorms and floods affects social production to various degrees. The loss range of China’s total output caused by rainstorms and floods in 20082016 was [3525652, 40536761］billion yuan. In the long run, the cumulative effect of disasters cannot be ignored. The occurrence of rainstorms and floods will not only affect the social and economic development of that year, but also have a significant impact on the economic development in the later period. The results obtained are a useful supplement to the study of disaster economic losses, and can serve as empirical support for government and other departments to carry out postdisaster emergency management.