In order to improve the mechanics performance of pour asphalt concrete , the maximum particle size of aggregate is increased from 31.5mm and 19mm. By using uniform orthogonal design method ,the paper carried out the mix design of asphalt concrete and selected the optimal mix proportion.The result indicated that the increase of the maximum particle size of aggregate decreases the amount of asphalt.The stability and density of Marshall is evidently increased and the flow value is decreased. The mechanics performance is close to that of roller compacted asphalt concrete .The result can provide reference for the application of core wall of pour asphalt concrete in medium and high dam.