It is crucial measuring position and attitude of model to gain the precise and accurate data in wind tunnel tests. The model displacement videogrammetric measurement (MDVM) system and its key techniques such as the exterior orientation with big rotation angles and large-overlap, mark points, image processing and calibration based on the known distances are therefore presented. The practice example in Asia's largest (2.4m) transonic wind tunnel has demonstrated the MDVM system and its key techniques are correct and feasible, and they have application value.