Abstract: Free flight test can obtain aerodynamic parameters using the model's motion trajectory, which was recorded by high speed camera. It has unique advantages in the study of aircraft dynamic/static stability for its characters of no support system because of its true simulation of the flight condition. A free flight test was carried out in the JF-8A hypersonic wind tunnel with a 10°cone model, simultaneously, a ball model was used to measure the dynamic pressure. In this paper, the key method of extracting motion parameters and aerodynamic characters were also introduced in detail.