Based on daily thunderstorm data， topography data， temperature data in Hainan for the period of 1966 to 2005 and radiosonde data from 2004 to 2006， the possible causes of the spatial and temporal distribution patterns of summer thunderstorm in Hainan are analyzed. The results show that: (1) In most parts of Hainan， thunderstorms mostly occur around afternoon time， while in Sanya thunderstorms happen mainly in night time. (2) The landsea breeze convection shear induces thunderstorms frequently in summer in north and west coast areas， and thunderstorm mainly occurs at afternoon， whose main reason is the convection of the local northerly from sea and largescale southerly. In Sanya， thunderstorms mainly happen at night because of the convection of the local northerly from landsea breeze and the southerly of the largescale environment in nighttime, but not in the daytime. (3) Thunderstorms are closely in associated with the local heat convection in the northern inner land and the western Hainan. Topography also shapes the spatial distribution of thunderstorms. The activities of thunderstorms in the Wuzhishan mountain area are more frequenlt than those in other areas around. Topography also affects the daily distribution of thunderstorms， mainly in north of the Wuzhishan mountain. (4) The seasonal distribution of thunderstorms in Hainan is mainly influenced by radiation in the Haikou area. (5) The heat fluxes can well account for the seasonal variation of thunderstorm activities in the Haikou area; and the anticorrelation between thunderstorm days and Bowen ratio (ratio of sensible to latent heat flux) of the wholeday heat flux is much higher than that at noon.