The regional climate model (version 3, RegCM3) with a horizontal resolution of 50 km was employed to downscale the historical climate change and projected its future scenario over CORDEX (COordinated Regional Downscaling Experiment) East Asian domain. Model RegCM3 was nested within the global climate system model FGOALS-g2. The simulation of summer surface air temperature and extreme high-temperature events over China was evaluated first, and summer surface air temperature changes under the RCP8.5 scenario over China were then compared between model RegCM3 and model FGOALS-g2. Results indicate that both models reasonably reproduced the climatological distribution of surface air temperature and extreme high-temperature events. Compared to the driving global climate model, the detailed characteristics of summer surface air temperature were better simulated in model RegCM3 due to its high horizontal resolution. Under the RCP8.5 scenario, summer surface air temperature over China will increase significantly during the middle of the 21st century. In the projection of model FGOALS-g2, the spatial patterns of the changes in the three temperature indices were similar with larger increases over northeastern China and the Tibetan Plateau. In addition, the range of changes in daily temperature is small in model FGOALS-g2. However, model RegCM3 projected a larger increase in daily maximum temperature (Tmax) compared to the increase in daily minimum temperature (Tmin) over most regions of China, thereby daily temperature range would become large in these regions. In the western Tibetan Plateau, the projected increase in Tmin was larger than that in Tmax and daily temperature range became smaller. Extreme high-temperature events were projected to increase significantly in both models. Warm days (TX90p) will increase more than 60% compared to present day, while the warm spell duration indicator (WSDI) will become twice of that of present day.