Abstract: The mean daily temperature is a major indicator reflecting climate characteristics, there are many ways to calculate the mean daily temperature. In order to find out the influence of different calculation methods on the mean daily temperature, on the basis of data from 5 national benchmark stations of Hebei Province, 3 kinds of omputational methods including the extreme value average, 4 times average and 8 times average were adopted to count the mean daily temperature and analyze the result in comparing with the actual daily average temperatures. The results indicated that the correlation coefficient between the 3 kinds of calculation methods of the mean temperature and the actual average temperature series was higher than 0.9. The mean temperatures calculated by 8 times average was the closest to the actual average temperature, averagely lowered for 0.0052℃; the extreme value was 0.4568℃ higher than the actual average temperature; the 4 times average was 0.1789℃ lower than the actual average temperature. The temperature increasing rate of the 24 times was the smallest, and the rate of 10 a was close to 0.33, higher than the results of previous studies. The estimation accuracy of the 3 kinds of calculation methods was between 10-7 and 10-4, which was relatively high. Under the premise of ensuring the length of the data and the number of stations, these methods can well represent the climate change trend.