The influence of different calcination temperatures and times on the whiteness, alumina content, and dissolution rate of coal gangue from Ordos City were studied. XRF, TG-DSC and high-temperature calcination were employed to analyze the chemical composition and thermal phase transitions of the coal gangue. The results show that calcination can effectively remove fixed carbon and promote the whiteness. The content of Al2O3 increases with the increase of calcination temperatures and times during the temperature range from 650 to 850 ℃, and the dissolution rate of Al2O3 also increases as the calcination time increases, however, when the temperature is higher than 950 ℃, the dissolution rate of Al2O3 decreases dramatically. The soaking time increases with the raising whiteness of the caicined coal gangue samples. And the whiteness increases as the heating-up time increases, and the coal gangue has sufficient time to fully decarbonize.