Global warming has resulted in devastating hazards for human society,such as floods,droughts and heat waves.The Dongting Lake Basin is a region characterized by frequent heat waves and high temperatures in summer.Severe heat waves had brought enormous influences on human health and agriculture in this area.Take the 2013 heat wave as an example,it caused water shortage of more than 3 million people and 1.2 million animals,and resulted in loss of about $ 0.18 billion.In recent years,many researchers have focused on the warming characteristics.However,most of this studies focused on the trends of several single indices,while few studies have studied the probability,especially the joint probability of heat waves.On the other hand,duration and temperature are the two inherent characteristics of a heat events,hence,analysis of the joint probability of the two indices could improve our knowledge of severe heat events and for helpful hazards prevention in this region. Therefore,based on the ground surface observed daily temperature dataset(1960-2013),this study investigated the spatial-temporal characteristics and the risks of extreme heat events (EHE)in the Dongting Lake Catchment,by using MK test,probability distribution and copulas.Four indices,i.e. length of heatwaves(HWL),mean max temperature in heatwaves(HWT),hot days(HDL)and mean max temperature in hot days (HDT)were employed to reflect the extreme heat events.The results showed that,the four indices decreased first and then increased obviously after 1987.The amplitudes of EHE were relatively high in eastern and southeastern parts of the catchment,and were relatively lower in western and southwestern parts.Furthermore,though there existed heterogeneous patterns,the amplitude and risk of EHE after 1987 in this area overall increased compared to that in 1960-1987.In particular,the regional mean of 5-year return levels for HWL,HWT,HDL and HDT(HWL_5,HWT_5, HDL_5 and HDT_5)increased by 0.5 day,0.2℃,2.0 day,and 0.2℃,respectively.Moreover,the copula results indicated that the risks of serious heatwaves had increased in the major part of the basin,and decreased in southwestern and southern parts.