To investigate the influence of rusty aggregate on the mechanical properties of dam concrete, we conducted comparative test on the compressive strength, splitting tensile strength, as well as axial tensile performance of wet-screened and fully-graded concrete specimens with different aggregate conditions. Our findings unveiled that rust adhered to the surface of rock with a thickness of about 3-5 mm; the strength of rusty aggregate was slightly lower than that of conventional aggregate; splitting and peeling occurred in the loading process. Rust reduced the mechanical properties of concrete: the compressive strength, splitting tensile strength and axial tensile strength reduced by less than 5%,10% and 13%,respectively; but such reduction rate dropped with the increase of age. The splitting tensile strength, axial tensile strength and ultimate tensile value of fully-graded concrete were 70%-79%,56%-62%,and 56%-63% of those wet-screened concrete, respectively. In addition, we observed ultra-large and large aggregates distributed uniformly in the specimen and visible rust stains in the sections. The research findings offer technical support for the impact evaluation of rusty aggregates and their reasonable application in dams.