Background: Several studies demonstrated a short-term association between ambient temperature and blood pressure.However, few studies have assessed the long-term effect of ambient temperature on childrens blood pressure.The present study aimed to investigate the associations between long-term exposure to local ambient temperature and childrens blood pressure in China.Methods and Results: We analyzed the systolic (SBP) and diastolic blood pressure (DBP) data of 71,763 children from 2010 Chinese National Survey on Students Construction and Health (CHNSCH), and local annual average ambient temperature, relative humidity, air pollutants data from China Meteorological Administration and Ministry of Environment Protection of China.We used General additive model (GAM) with non-linear function to examine the effects of ambient temperature on childrens blood pressure.The results showed that decrease of ambient temperature was negatively associated with increase of both SBP and DBP in Chinese children while adjusting for individual characteristics, socioeconomic conditions, air pollutants and relative humidity.The largest alteration of SBP related to the temperature difference was observed from 20.2℃ to 9.8℃, with 10.7 mmHg (95%CI: 10.66, 11.41) increase in SBP, while the largest alteration of DBP was observed from 24.6℃ to 10.3℃, with 7.8 mmHg (95%CI: 7.50, 8.16) increase in DBP.However, when temperature below 9.8℃ and 10.3℃, SBP and DBP started to decrease, which might been caused by the use of heating system in the extreme cold areas.The similar association was found in either physically active or inactive children.Conclusions: Public health policy should be improved for protecting childrens cardiovascular health from adverse effects of low temperature.Development of heating system in moderate cold area might be a good solution