Eutrophication under climate warming is a hot topic in limnology recently.Our study demonstrated that epilimnetic total phosphorus (TP),total nitrogen (TN) and air temperature increased with the process of eutrophication in Lake Erhai in 1980-2009.Statistics analysis demonstrated that,air temperature promoted the growth of phytoplankton with no effect from TP and TN, TP promoted the growth of phytoplankton with no effect from air temperature but with effect from TN,TN promoted the growth of phytoplankton with no effect from air temperature and TP individually but with effect from their interaction.Climate warming and nutrient enrichment promote eutrophication of Lake Erhai together.