The variation characteristics of average maximum temperature, the number of high temperature days, and the dates of the first and last days of high temperature occurrence are analyzed with the observational data from 1953 to 2005 in Hefei, based on the moving t test technique, etc. The results indicate that the changes of the average maximum temperature shows an increasingdecreasingincreasing trend, with the abrupt changes taking place in 1968 and 1988. The change of the number of high temperature days shows an increasingdecreasingincreasing trend, without evident abrupt change. High temperature days occurred mainly from May to September, most frequently in July (49.7%) and secondly in August (40.5%). The high temperature duration in Hefei underwent a longshortlong change, with the shortest in the early 1980s.