Abstract: Using the hourly precipitation datasets from April to September of 2019, and the hourly datasets ERA-5, the temporal and spatial distribution characteristics of flash-heavy-rain in Chengdu in the past ten years were studied. According to the basic conditions for the occurrence and development of flash-heavy-rain, and the notion of basic ingredients, the probability forecasting of flash-heavy-rain in Chengdu was discussed. The main results are as follows: The flash-heavy-rain events in Chengdu are concentrated in the warm season (from April to September), of which July is the most frequent, and it appears to be more frequent at night. The spatial distribution of precipitation and precipitation intensity is more in the west and less in the east. The selected flash-heavy-rain potential prediction factors including 850mb Specific Humidity, 850mb Equivalent Potential Temperature, K Index, CAPE, 700hPa Meridional Wind and 700hPa Vertical Velocity, which basically covers the water vapor conditions, stability conditions and uplift conditions required for flash-heavy-rain. Based on the weight coefficient of the above flash-heavy-rain potential forecast factors, the probability forecast equation of falsh-heavy-rain was estabilished by dichotomy. The testing result of 2019 shows that when the threshold is set to 0.98, the quantity of omission days and correct days are acceptable, while maintaining a high accuracy rate.