As solid precipitation, hail is a kind of high-impact weather in China and also play an important role in the hydrologic cycle in the world. Because recent observation show an increasing of extreme precipitation events under the global warming, the study of the climatology of hail and its long term trend will help us to understand the change of extreme precipitation. Hail frequency and intensity is poorly known in the past due to the limit of hail observation system in China. This project will provide new insight to hail climatology and its long term trend from 1960 to now, using the historical surface record, satellite observation and simulation with high-resolution mesoscale model. We plan to describe the detail climatology of hail frequency and intensity, try to understand how and why they change with the changing environment, and finally, to project their change in the future. This research will provide theoretical clue to the decision maker to prevent disaster of China in the future.