Abstract: In this study，the C30 and C50 ordinary concretes were prepared with washed dredged sand，and unwashed dredged marine sand． Compared to concrete made with river sand，the resistance to sulfate attack of the above concretes was studied by dry-wet cycle test． The results show that the mass loss of the concrete under sulfate attack is related to the surface deterioration． In terms of the same strength grade，the sulfate attacking resistance of washed dredged sand concrete is better than that of the concrete made with river sand． In addition，the chloride from the unwashed dredged sand affects negatively on the resistance to sulfate attack of concrete．