Based on the data of environmental multi-proxy of lake sediments from Core 2 in Lake Swan, one of the tail-lakes of Heihe River, the contained information of climate changes and human activities is distilled. The evolution of Lake Swan during recent 200 years is divided into 7 phases according to the information recorded by lake sediment. In each phases different factors affected the lake evolution on different levels, and the combining effect of both climate changes and human activities led evolution of Lake Swan and the environmenta changes of Ejina Oasis. The natural climate change played a leading role in the process of evolvement of Lake Swan during recent 200 years, and human activities affected the lake environment greatly especially in special periods.