The effect of different fineness of limestone powder on the properties of cement concrete were studied. The results show that the fine grinding of limestone powder make cement standard consistency water drop slightly and shorten the initial setting time and final setting time, and make the concrete mixture slump increase, and could increase liquidity and plasticity of mixture;Measurement results of different age concrete block show that the compressive strength of ground limestone powder increase the strength of concrete, and with the increase of the limestone powder fineness, the compressive strength of concrete block value increase.