The data of conventional meteorological observation in the Qinghai Lake Basin and at the peripheral meteorological stations during the period more than 50 years were used to analyze the changes of extreme weather and climate events including temperature,precipitation and wind speed. The potential impacts of these changes on the change of water level of the Qinghai Lake and natural environment were discussed. The results showed that the average annual temperature and the extreme temperature in the Qinghai Lake Basin were significantly increased. Annual days of strong wind were in a decrease trend in the upper reaches of the basin. Annual precipitation was slightly increased,but the days of precipitation were decreased. Especially the frequency and intensity of heavy precipitation at Gangcha Meteorological Station in the upper reaches was increased. There was a significant positive correlation between the change of water level of the Qinghai Lake and the annual precipitation in previous year. Water level of the Qinghai Lake was changed from a negative balance to a positive one in recent years under the effect of warming-wetting climate change. The increase of precipitation had an active effect for water and soil conservation, reduction of wind speed,improvement of sand fixation and ecological regeneration in the basin.