Abstract: Due to its unique geographical location, the Sichuan region has the highest cloud cover in China, but with significant spatial heterogeneity. Based on ISCCP-H cloud data from 1998 to 2016, the distribution characteristics of cloud amount and cloud water path of different cloud types in Sichuan during the warm season (May—September) were investigated. Combined with CMORPH precipitation data, the relationship between cloud amount of different cloud types and precipitation in Sichuan was explored by region and precipitation level. The main results are: (1) The plain area represented by Chengdu is the region with the largest distribution of cumulus clouds, the high mountain area represented by the transition area between the West Sichuan Plateau and Sichuan Basin is the region with the largest distribution of stratocumulus and stratus clouds, the West Sichuan Plateau is the region with the largest distribution of altocumulus, cirrus and cirrostratus clouds, the South Sichuan Mountain is the region with the largest distribution of water deep convective clouds, the North Sichuan Mountain is the region with the largest distribution of ice deep convective clouds. The distribution characteristics of stratocumulus and stratus clouds are similar to those of precipitation in Sichuan. The transition area between the West Sichuan Plateau and Sichuan Basin is the high value area of stratocumulus and stratus clouds, and its center is located in Ya'an and Leshan, which corresponds to the high value area of precipitation and precipitation center of Sichuan, which is known as the "rain zone of west China". (2) Clouds in Sichuan can be classified into 12 types: stratus, stratocumulus, water cirrostratus and water deep convective clouds with relatively low cloud cover but a larger cloud water path; cumulus, altocumulus and ice cirrus clouds with higher cloud cover but a smaller cloud water path; water cirrus clouds with low cloud cover and a smaller cloud water path; and altostratus, nimbostratus, ice cirrostratus and ice deep convective clouds with high cloud cover and a larger cloud water path. The highest frequency of cloud occurrence is observed in the high mountain areas, where the total cloud cover reaches 91.4%, while the average cloud water path is the smallest at 204.3 g/m². (3) Low cloud cover is negatively correlated with precipitation in Sichuan, while high cloud cover shows a positive correlation. In plain areas, the cloud cover of various cloud types is strongly correlated with precipitation across different intensity levels, with the most significant correlation between high cloud cover and precipitation. The high mountain area, a region of high precipitation, indicates that the undulating steep terrain is conducive to the conversion of cloud water into precipitation. In the northern Sichuan mountain area, which has the highest cloud cover and the largest cloud water path of ice deep convective clouds, the cloud cover of this type shows a significant positive correlation with precipitation at all intensity levels.