As a new conceptual micro air vehicle, biomimetic flapping-wing robots have the advantages of small sizes, light weights, high maneuverability, and perfect aerodynamic performance. Flapping-wing robot can produce more effective aerodynamic force than traditional fixed-wing or rotary-wing aircrafts. Unsteady aerodynamics at low Reynolds number is the main theory applied to micro air vehicle analysis. In this paper, the flight parameters for a flapping-wing robot are designed with geometric similarity firstly. Then an improved aerodynamic model with optimized parameters is established. Lastly, some simulation and analysis are presented to illustrate and verify the feasibility and effectiveness of the models.