Abstract: The head junction of Zhala Hydropower Station has the engineering constraints of an asymmetric narrow valley, compact building layout, complex geological conditions, and requirement of ecological flow.Combined with the characteristics of the project, two energy dissipation schemes of ski-jump and underflow are preliminarily proposed.The flow pattern, pressure characteristics, flow velocity and riverbed erosion under two different schemes were analyzed by a hydraulic model test.At the same time, the building layout, water atomization, construction condition and technical-economic conditions under the two schemes were also compared.The results showed that the underflow energy dissipation scheme had sufficient energy dissipation, small atomization and scouring, excellent building layout, less influence by flood discharge and better construction conditions.Although the economy of the underflow energy dissipation scheme was slightly worse than that of the ski-jump scheme, it had better safety and adaptability.Finally, the underflow energy dissipation scheme was selected as the recommended flood discharge energy dissipation scheme.The relevant results can be a useful reference for the design of flood discharge and energy dissipation of similar projects.