Based on the wave reflection principle, a floating flapping-panel wave energy converter was developed. The feasibility study and optimization study of the new WEC was carried out by laboratory research and computational fluid dynamics techniques. A numerical model was developed for an in-depth study to establish the relationship between slope tilt angle and power. The results for different wave periods show that the power take-off damping coefficient has a significant effect on the power. Meanwhile, the effects of flap length and wave height on converter resonance and power are investigated. Finally, a preliminary laboratory physical model test of the device is conducted. The flapping-panel-slope structure is very feasible and effective with good hydrodynamic performance.