Abstract: Albatrosses can achieve gliding for thousands of kilometers with the gradient wind. This wind energy utilization behavior is very valuable for flapping-wing robot. To explore this possibility, this paper optimizes the optimizes the gliding performance of a self-developed flapping-wing robot by referring to the large aspect ratio and high lift-to-drag ratio gliding characteristics to birds such as albatrosses. To satisfy the requirements for wind energy utilization research, this paper proposed a flapping/gliding mode switching device based on a ratchet stop mechanism and a flapping phase detector. Then, aerodynamic simulations are performed on the optimized flapping-wing robot to obtain the lift and drag coefficient at different angles of attack. Trajectory optimization research is carried out to obtain the optimal gliding trajectory of the bionic flapping-wing robot under different flight path angles, which combined with the gradient wind field model and the gliding attitude kinematics model. At last, gliding trajectories with flight path angles of -30°, 0°, 30° and 60° are selected for flight experiments. The experimental results show that the energy consumption of gliding flight is significantly lower than flapping flight over the same distance, and prove that the bionic flapping-wing robot can achieve wind energy utilization.