For a temperature rebound in the irrigated high arch dam, a statistic analysis is carried out, with consideration of the temperature rebound values in the irrigated area about the extra high arch dam, Xi Luo Du which is under construction. The irrigated concrete block, without impounding water, is approximately simplified as a concrete slab, and the irrigated temperature rebound phenomenon is analyzed, based on the theory of the natural cooling or rebound of the concrete. It shows that the current high arch dam's closure temperature is lower than the dam site's average temperature, so the dam site's temperature inevitably would flow backward, slowly, to the irrigation area. Moreover, the theoretical temperature rebound value is close to the actual temperature rise in the irrigated area. Therefore, the main cause of the temperature rebound in the irrigated high arch dam is that the environment temperature flows backward, slowly, to the irrigation area.