Two sediment cores were collected in different areas of Lake Bosten in Xinjiang. Based on ²¹⁰Pb and ¹³⁷Cs dating, chlorophyll-a content analyses using the method of diffuse reflection spectrum, and in combination with studies on deposition rate, loss on ignition and runoff records of Kaidu River, the changes of primary productivity of Lake Bosten during the past 100 a were discussed in this paper. The results showed that runoff changes of Kaidu River have some influences on the dry mass accumulation in Lake Bosten, but the impact of human activities is the main reason for the variation of primary productivity. As a result of Xinjiang's first large-scale reclamation in the 1950s, the deposition rate and the primary productivity of Lake Bosten started to rise. The peak of the deposition rate and chlorophyll-a accumulation rate of the lake sediments appeared in the 1970s, which was related to the Xinjiang's second large-scale reclamation, and the desalting of alkaline soil also played a significant impact on the ecological change of Lake Bosten. From the 1980s to present, with the intensification of the human activities in surrounding areas, chlorophyll- a content of the lake sediments gradually increased, and the primary productivity of Lake Bosten showed an increasing trend.