A 1/10 scale model for the ventilation system of the underground powerhouse of Ganhe Pumping Station was established on the basis of numerical simulation and similarity theory to study the feasibility of the pumping station's ventilation system . The model tests contained 9 different working conditions, such as different seasons, different supply air temperatures and different numbers of operating units. The interior parameters of all regions in the underground powerhouse were tested, and the test data were analyzed. Experiment results have shown that the highest and the average interior temperature is 29.46 ℃ and 27.72 ℃ respectively in summer when the supply air temperature reaches 24.5 ℃. The scheme for the ventilation system meets the requirements of relevant standards. The indoor temperature is lower in transition seasons and in partial loading condition. Therefore, VAV system can be used in the ventilation system in order to achieve further energy saving.