Abstract: Pumped storage power station has great development prospects. Due to the special conditions of marine environment,a pumped storage power station in the island is facing various problems. This paper takes the underground plant in the site of a southern island as an example to introduce its designing philosophy of ventilation system,ventilation process,salt spray control and confronted problems. Besides,it analyzes countermeasures for problems from the aspects of air process,air speed and air intake to provide references for the design of ventilation system of the pumped storage power station in the island.