The land surface temperature in summer in Haidian district, Beijing in 2004, 2009 and 2017, was inverted by the single-window algorithm on the basis of the Landsat image data. The variation characteristics of urban heat island effect were analyzed quantitatively, and the causes of heat island effect were discussed. The results showed that: 1)During 2004 to 2017,the urban master planning positioned Haidian district as a livable city and required it to build a high-quality greening system. Through the construction, the proportion of heat island area in Haidian district fell to 34.12% from 36.22%, which was stronger in southeast than northwest in spatial distribution and diffusional over time. 2)Several newly-added strong heat island areas in Haidian district, were mostly related to the increase in built-up land area as well as increase in height and density of buildings. Improved urban greening didn't work well in decreasing temperature, but sizable parks or green lands did. During 2004 to 2017, the proportion of built-up land in Haidian district fell to 48.72% from 52.13%, and then rose to 51.44%, the proportion of unused land fell to 6.23% from 9.27%,and then rose to 9.18%, the proportion of green land rose to 39.32% from 30.46%, and then fell to 36.20%, which were consistent with the trend that the proportion of heat island decreased and then increased in Haidian district. 3) Traffic conditions also had an important impact on the enhancement of urban heat island effect, and led to generate other potential heat sources as well. This paper aims to provide conditions for finding effective measures to control the heat island effect by studying the law of heat island effect changing with land use and traffic conditions.