A new type of trajectory capture system(CTS) mechanism was proposed for the traditional CTS with high blockage and low position accuracy in transonic wind tunnel. The composition and working principle of the CTS system were introduced, then its mechanical system was designed and analyzed. In order to verify the rationality of the mechanism, the blockage and stiffness of the mechanism were analyzed, and based on the 6-DOF kinematic equations, the position error model of the mechanism was established. Finally, the position error of the system was analyzed based on Monte-Carlo method. The analysis results show that the blockage, stiffness and position error of the new CTS mechanism meet the design requirements and are superior to the original mechanism.