Abstract: Flexible nozzle has to be designed long enough in order to ensure the elasticity of the nozzle wall material. The characteristics of long-span, large amount, complex structure of the actuators bring enormous challenge to the design of the flexible nozzle contour control system. It is not only needed to control the positon of each actuator precisely, but also to control motion axes for synchronization. The effect of synchronization control has a direct impact on the flexible plant forming quality and the wind tunnel flow quality. To solve the accurate positioning, multi-axis proportion synchronous control problems and to ensure safety of the full flexible nozzle in the new trans-supersonic wind tunnel of China Aerodynamics Research and Development Center, key technologies are researched. A virtual axis with the gearing synchronization strategy is proposed the redundant position technology axis is established and the control parameters is optimized based on SIMENS SIMOTION D and S120 motion control platform. The test results of actuators' displacement and servo motors' speed are analyzed based on the experiment of the multi-axis proportion synchronization motion system. The results show that the control system possesses complete functionality, that all the actuators can move uniformly in the range of 0~1mm/s, the tracking error is less than or equal to ±0.01mm/s, the proportion synchronization error is less than or equal to ±0.02mm/s, and the contour error before and after the nozzle throat point is less than or equal to ±0.2mm and ±0.06mm. The synchronization control precision and repeatability accuracy can meet the engineering application request and achieve good effect.