The variation characteristics of average maximum temperature and high temperature days were analyzed by the linear trend method, sliding average method and the wavelet translation method, based on the daily maximum temperature in Kunshan from 1961 to 2010. The results showed that average maximum temperature increased with slight fluctuation. The average maximum temperature had an obvious increasing trend since late 1980s. Its oscillation period was 24 a, 15 a, 10 a and 4 a. The change in the number of high temperature days showed an obvious increasing trend since 1990s, especially since 2001. The first days of maximum temperature had an earlier trend and the last days of maximum temperature had a later-earlier-later pattern. The high temperature duration was increased gradually. High temperature processes occurred from the last ten days of June to the first ten days of September. The maxi mum number of each type of high temperature process belonged to July, while August took second place. In the first ten years of the 21st century, there was the maximum number of each type of high temperature process appeared most frequently.