In this paper,the aerodynamic performances of a biomimetic flapping-wing robot is investigated based on the modified blade element theory,and the flap and the twist models for a robot in meso-and-micro scale are established in the conditions of low Reynolds numbers and unsteady aerodynamic behaviors. Then,the attack angle is modified according to the downwash effect caused by unsteady wake flow,based on which the numerical models of the lift force and the thrust force are presented. The experimental results basically accord with the simulated ones,showing a similar tendency of aerodynamic forces during the downstroke and upstroke of the robot. Finally,based on the proposed models,the flying mechanism and aerodynamic characteristics of the flapping-wing robot are further analyzed. It is found that the lift force is generated by both the inner and the outer wings,while the thrust force is mainly by the outer wing; and that,as compared with the lift force,the thrust force is more sensitive to the flap frequency. It is thus concluded that the proposed method is effective in the aerodynamic analysis of biomimetic flapping-wing robots.