The stochastic nature of wind and solar power and the uncertainty of electricity price create potential risks for bidding. The combination of the wind farm, PV station and pumped storage plant can reduce the influence of uncertainties of the wind and solar power and the electricity price. An optimization model for joint bidding strategy of a wind-solar-pumped storage system in joint energy and ancillary service market is developed and the stochastic information gap decision theory (IGDT) is introduced into the model to measure the influences of the uncertainty values. In order to confirm the validity of the bidding strategy, the results of four cases are analyzed through comparison. The simulation results show that the profit of system increased by 7.64% under the proposed method compared with only participating in energy market. The stochastic-IGDT based bidding strategy can effectively handle the uncertainty of wind and solar power and electricity price.