Abstract: Weizhou Island (109°00'～109°15'E,21°00'～21°10'N) locates in the north coral reef distribution belt of the South China Sea.In such relatively high latitude area,sea surface temperature (SST) is an important factor affecting the development of coral reef ecosystem.Measurements of the latest 42 years' SST of Weizhou Island showed that with 3～4 years and 7～8 years fluctuating cycles,the SST almost had a synchronous increase with global warming,especially since the later 1980s.Overall,the coral reef of Weizhou Island could benefit from the SST warming,especially the cold months SST increase,because it's the north margin of tropical zone.But,the warming of the warmest month may be a thermal stress on the development of coral reef.It reaches the upper limits of coral reef development,and leads the coral reef bleaching.Mankind activities,including wide scale building,oil gas factory near the island,traveling,fishing and breeding,may be also the potential stresses on limiting the coral reef development.The combination of summer warming and mankind stress is possibly to destroy the coral reef ecosystem of Weizhou Island.Based on a detailed field investigation,the modern coral reef distribution map around Weizhou Island was described.