The seepagestress field and the interaction of sulfate and chloride salts on highperformance concrete of underground structure are simulated by experiment to reveal the degradation rules of underground highperformance concrete; and the compressive strength of the concrete after corrosion is detected and the corrosion products in the corroded concrete are analyzed. The results show that: 1) When the load varies independently, the larger the load is, the more obvious the erosion is. 2) When the water pressure varies independently, the greater the waterhead difference is, the more serious the corrosion is. 3) The effect of the waterhead difference on concrete compressive strength is higher than that of load; but with the increase of the waterhead and load, the effect of them becomes almost the same. 4) Compares to single factor, the concrete compressive strength decreases more under two combined action; the concrete corrosion situation will be more serious under the combined action of load and waterhead difference. The micro test and analysis show that the load and waterhead difference will fasten the formation of corrosion products in concrete; the test result of effect of waterhead difference on concrete compressive properties is the same with analytical one.