A statistical analysis is carried out on the simultaneous observation data of the temperature inside and outside the thermometer shelter in Changsha during summer in 2011 and 2012 The results show that the temperature outside the thermometer shelter is higher (lower) than that inside the thermometer shelter in the daytime (nighttime). However, there exists a similar variation trend for average temperature and extreme maximum temperature inside and outside the thermometer shelter. The average temperature and extreme maximum temperature outside the thermometer shelter is higher than that inside the thermometer shelter. Furthermore, there exists difference between temperature inside and outside the thermometer shelter during different weather conditions，with an average difference of 12 ℃ in rainy days, 28 ℃ in sunny days, and 31 ℃cloudy days. The difference of extreme maximum temperature inside and outside the thermometer shelters is up to 64 ℃. Especially, the number of days with the extreme maximum temperature inside the thermometer shelter higher than 35 ℃ is 61 days in two year, and that inside the thermometer shelter up to 125 days. The extreme maximum temperature inside and outside the thermometer shelter is 389 ℃ and 420 ℃ respectively. Therefore, the difference between temperature inside and outside the thermometer shelter should be taken into account in high temperature forecast and public meteorological service.