Rotating nozzle profile enables the supersonic variable Mach number wind tunnel to continuously adjust the Mach number of the experimental area during a single operation, which is important for studying the aerodynamic problems in the maneuvering process of the aircraft and the starting process of the inlet. In the process of controlling the nozzle profile rotation, whether the flow field parameters can change linearly is an important criterion to measure the performance of supersonic variable Mach number wind tunnel. Therefore, this paper analyzes the linear variation law of flow field parameters in the experimental area of variable Mach number wind tunnel, and a numerical simulation model is established using the spring smoothing dynamic grid technique to verify whether the flow field parameters in the experimental area meet the linear variation law when the nozzle is located at the corresponding position of Mach number 3.041~3.215. The results show that the linear change of the flow field parameters in the wind tunnel experimental area is achieved by controlling the rotation of the nozzle profile, and the dynamic calculation results are in good agreement with the expected linear change law of the flow field parameters in the experimental area. In the linear change process of flow field parameters with different accelerations, the deviation between the average parameters of the experimental area and the expected parameters at each time is less than 0.13%.