The characteristics of temporal and spatial distribution of hails over Yunnan Province were analyzed by using of the recent 40-year hail data, to reveal the variation regularities of hails and main influencing factors. The analysis shows that the seasonal distribution of hails was very complicated. The peak values usually occurred in spring and summer. The seasonal distribution of hails was related with elevation: generally in springtime hails happened more frequently at lower-elevation areas, and in summertime at high-elevation areas. The inter-annual change of the numbers of hailing days in the western Yunnan was more obvious than in the eastern Yunnan, while the inter-decadal change of hailing-day numbers was more obvious in the eastern Yunnan than in the western Yunnan. The numbers of hailing days in mountainous and high-elevation areas were greater than those in basin or plain areas and lower-elevation areas.