Model attitude and position measurement technique plays a key role in the wind tunnel free flight test. At present, the pose will be determined by a vane system mounted near the nose of the model or IMU and AHRS in the model. The larger vane sensor will add the difficulty in system modelling and identification for the intrusion of the model surface flow field, and the inner sensors will occupy the limited internal space of the model, making it hard to design inertia similarity model. An motion capture system, OptiTrack, is used to measure model attitude and position. Static tests indicate that the system has position accuracy of 1 mm and angle accuracy of 0.05°, and good dynamic performance meets the requirements of data sampling rate better than 100 Hz. OptiTrack system shows better robustness compared with AHRS. The position obtained by the OptiTrack system can be used for model flight around a fixed point in the wind tunnel, which lowers the test risk effectively.