An aero-optical evaluation method was presented for the investigation on high speed flow’s aero-optical characteristics. The refraction factor which could denote the aero-optical effects of flowfield was derived from the principle of refraction. The planar stabilities of refraction factor distribution in mean flow and refraction factor fluctuation in fluctuation flow were statistically estimated. The integrative evaluation was the combination of two statistical planar stabilities. The result shows that the mean flow’s aero-optical effects are mainly caused by the shock wave while the fluctuation flow’s aero-optical effects are caused by turbulence boundary layer. The flow’s aero-optical effects reaches minimum when the angle of incident ray is near 45 degrees. The aero-optical effects grow stronger as the Mach number increases. The aero-optical effects become weaker as the angle of attack increases. The results agree well with the theoretical predictions, and it is practical for engineering application.