Due to the large specific drop of river and high sediment content in flood season, the design of sluice in mountainous area usually adopts apron energy dissipator to connect with the downstream river. Based on the physical model test of a hydropower station, this paper makes a comparative study of the two connecting forms of the anti-arc apron and the straight slope apron. By comparing the flow pattern, flow field distribution and downstream riverbed scour, the results show that the anti-arc apron is obviously superior to the straight slope apron in terms of flow pattern and downstream riverbed scour. Specifically to eliminate the left-side reflow of the apron. The maximum scouring depth is reduced by 38%. However, at the downstream low water level, the shore flow velocity of the two banks is larger than that of the straight slope apron, with the average increase of 12.5% on the right bank. Considering comprehensively, if the mountains on both sides are relatively complete, better engineering results can be obtained by adopting anti-arc apron.