Experiment was carried out to investigate the impact of natural aging of high reflective coating on its thermal insulation performance in hot-summer and cold-winter zone. White reflective coatings and gray coatings were applied respectively on two identical top-floor rooms of an office building in Chongqing with same floor area, envelope material and orientation. Thermal insulation performance was investigated by analyzing the records of three consecutive sunny day in July 2014 and July 2015. The results showed that reflectivity of reflective roof and thermal insulation performance decreased after one-year natural aging. When the room was conditioned with the setting point of 26℃, average temperatures of interior and exterior surfaces decreased by 3.2℃ and 4.2℃ respectively, and the energy consumption of air conditioners decreased by 0.03 kWh/m²·d in July 2014 compared with those in July 2015. When air-conditioners were off, there was a decrease of 2.5℃ in average indoor air temperature in July 2014 compared with those in July 2015.