The rear sting support mechanism of wind tunnel is a complex hydromechatronic system, which achieves continuous adjustment and accurate positioning of attack angle and sideslip angle through the coordinate movement of the attack angle mechanism, the front sideslip angle mechanism, the back sideslip angle mechanism and the Ydirection compensation mechanism. In order to solve the complex motion relationship between each mechanism and the accurate control problem of multiaxis motion, the motion equations of the sting mechanism was built by using kinematics analysis, which provided basis for accurate control. The pressure and flow computational formulas of the valvecontrolledcylinder system were presented, which provided basis for hydraulic system design and components selection. The velocity curves of the cylinder and pressureflow curves of the valvecontrolledcylinder system were shown, which intuitively indicated coordinate motion relationship between each mechanism and variation trend for pressure and flow of each servo valve.