Abstract: The cat-eye effect based active laser detection technique has a broad prospect in antimissile and air defense field, while the distortion effect on the incident and reflected waves caused by aerodynamic flow field around the planes and missiles is an important part of the echo wave characteristic analysis. Facing the complicated physical process of the laser waves in the cat-eye lenses and aerodynamic flow field both in the incidence and reflection propagation, a Zemax based aero-optical distortion calculation method was proposed. Firstly, based on finite element theory, the aero-optical flow field was divided into multiple layers according to the refractive index gradient. Secondly, curve surface fitting of the interfaces between the layers was done with standard, even asphere and Zernike polynomial surface, then a multilayer lens group model with different refractive index was established in Zemax, and the whole incidence and reflection Zemax model was accomplished with imaging optical system added in. Take a typical missile model as the example, the computational fluid dynamics and optical propagation distortion simulation in Zemax were performed, the feasibility of this method was validated after comparing with the analytical results of ray tracing.