In order to study the influence of temperature and air pressure on imaging quality of vehicle-mounted optical system,the influence of temperature variation and air pressure variation on structure parameters of optical system was analyzed. Taking CCD camera of a tracked armoured reconnaissance vehicle as an example,optical system model was established,and the system model was simulated and analyzed by setting different temperatures and air pressures. The imaging quality of optical system was characterized by the optical-modulation transfer function,and the change laws of imaging quality under different temperatures and air pressures were obtained. The simulation results show that the imaging quality of optical system becomes worse when the changes of temperature and air pressure are bigger,and the influence of air pressure changes is bigger than that of the temperature changes. The study has a great reference value for environmental adaptability design of new type vehicle-mounted optical system.