The temperature variation and seasonal difference around Beijing Fifth Ring Road are analyzed based on the observed air temperature of 1998-2009 of the Beijing Meteorological Observatory, Daxing Station and Fengtai Station, using the average of the data from Daxing and Fengtai stations as reference. Using the observed daily air temperature at 2 m in 2008 and 2009 from Beijing Meteorological Observatory and the stations within 20 km, the the representativeness of temperature data is studied through calculating correlation coefficient, the average of the absolute values of temperature differences, and the average of the absolute values of the differences between minimum and maximum temperature from Beijing Meteorological Observatory and those from other stations in Beijing. The results show that the average temperature in five years after the completion of the Beijing Fifth Ring Road increased by 098 ℃. The impact of the Fifth Ring Road on temperature data of the Beijing Meteorological Observatory varies from season to season. The increase is the biggest in spring and the smallest in autumn. The ratio of good representativeness of temperature is 521%. and the temperature from the Beijing Meteorological Observatory is well representative of average temperature of 0 to 5 km，5 km to 10 km，10 km to 15 km，and 15 km to 20 km zones.