The flowing fields of the arch-inverted form of plunge cushion pool and the flat-bottomed one, by the action of flood discharging of seven surface outlets, Xi Luodu high arch dam, were numerically simulated by using 3-d RNG k-ε turbulence model and rapid lid hypothesis applied in water surface. Firstly, the simulation results like the velocity at center and on both sides as well as the wall pressure were detailedly compared with those from the hydraulic experiment on the inverted-arch pool of Xiluodu, and It was proved that they were well accordant. On a basis of this, characteristics of the flowing condition, diffusion of the velocity near the wall and the wall pressure produced by both forms of the plunge cushion pool were detailly compared. The investigation showed that both had a good side and a bad one. On the impacting zone of jets, the flowing condition and the wall pressure distribution produced in the arch inverted pool were more reasonable, while there were zones of high pressure near corners to be easily damaged for the flat-bottomed. On its downstream and upstream reaches, those in the inverted were worse. The research provided a reference for the design, and had a very important signification.
