In order to realize the TECA (Transfer Equipment CAsk) automatic docking with the Tokamak vacuum chamber or the hot chamber window in ITER (international thermonuclear experimental reactor), a method for TECA posture adjustment based on the parallel lifting mechanism is proposed. A type of Stewart parallel lifting mechanism is designed for adjusting the posture of TECA transfer cask in nuclear environment. Firstly, a kinematics model is established after the structure and movement characteristics of the lifting mechanism are analyzed. Then, the process of inverse kinematics analysis is given, and the numerical solution of the forward kinematics is obtained by the Newton iteration method. Lastly, the double closed loop control algorithm is adopted to raise the docking speed and the precision. In field tests the parallel lifting mechanism can complete an accurate docking of the TECA transfer cask (4.25 m× 1.3 m× 1.75 m) with the vacuum chamber window at large scale, and the precision of repeated positioning is within 0.88 mm. The result shows that the proposed method is of fast speed and high precision in process of solving platform posture parameters.