Abstract: The method for preparation of fine powder of activated coal gangue and the effects of activated coal gangue on the properties of cement are experimentally discussed studied. The results show that the 28d compressive strength of cement mortar with 10% replaced content of activated coal gangue is close to or higher than that of pure cement mortar. When the replacement of activated coal gangue is higher than 30%, the strength of cement mortar is greatly decreased. However, the mechanical properties of concrete are enhanced when the cement is replaced by 30 percent activated coal gangue. And at the age of 7days, the relative chloride diffusion coefficient of concrete containing activated coal gangue is higher than that of pure concrete, but at the age of 180 days the relative chloride diffusion coefficient of concrete containing activated coal gangue is less than that of half's valume of pure concrete.