Abstract: Application of energy dissipators combining flaring gate piers, a stepped steep chute and a stilling basin is an effective way of solving the major problems of high-velocity flows that occur on high dams under large discharges per unit width and high working heads. But cavitation damage remains a possible threat to such overflow structures. In this study, we conduct scale model tests on a dissipator of this new type and compare its four design schemes, focusing on the hydraulic characteristics of Y-type flaring gate piers, stepped chutes and stilling basins. Scheme 1 has a steep chute with a regular staircase shape, and schemes 2-4 have a stepped chute section for transition of the step size. The results show that 1) Among the four schemes tested, the time-average pressure on the flip bucket scheme 1 is the highest, 3.3% higher than the other three schemes with a transition section. 2) The transitional shapes of the stepped chute produces greater effect on the negative pressure occurring on the step surface, and its value around the edge of the second step is the largest. The largest negative pressure (-0.33 kPa) of scheme 3 is the lowest of the four schemes. 3) In energy dissipation of all the schemes, the lowest dissipation rate is 51.71% in scheme 1 and the highest 52.77% in scheme 3.