Abstract: In order to design a more efficient and highly maneuverable flapping-wing aircraft, it is necessary to conduct meticulous aerodynamics research on the flapping-wing motion mechanism. The angle of attack is a key factor affecting the aerodynamic performance of a flapping-wing motion. Based on the Lattice Boltzmann method and the Level-Set moving boundary recognition method with the GPU acceleration, this work carries out the aerodynamic performance of flapping-wing with the angle of attack ( \theta ) from 0° to 60°. The results show that with increasing of \theta , the lift-to-drag ratio of the flapping-wing increases and then decreases. When \theta =10^ \circ , flapping-wing exhibits the best aerodynamic performance. In the range of \theta =0^ \circ \sim 40^ \circ , with increasing of \theta , the pressure difference between the upper and lower wing surfaces at the tip of the flapping-wing is greater than that at the root and middle of the wing, which provide greater lift force at the wing tip. As the \theta increasing, the area where the leading edge vortex attaches to the wing surface increases, and the vortices that fall off behind the flapping-wing are also difficult to dissipate, which lead to the increasing of the lift force of the flapping-wing. At the same time, the strength and range of influence of the wingtip vortex become larger, which lead to the increasing of the drag force of the flapping-wing.