Due to the excessive development speed， the rotation mechanism is often damaged by collision with the limit device when it is deployed to a predetermined form. For example， when the Falcon 9 rocket produced by SpaceX is deployed in the folding leg， too large a corner speed may lead to the destruction of the pin hinge of the leg. Installing a damper can slow down the speed of the mechanism and improve the safety of deployment， which is the premise and guarantee of the stable landing of the rocket. The traditional displacement damper cannot adapt to the speed， and there is a risk of sticking when applied to the mechanism development. However， the traditional high-pressure oil damper easily causes leakage and failure under high-speed operation. As a new type of velocity damper， eddy current torque damper can be used to slow down the angular speed of the mechanism. It has the advantages of no external power supply， no working fluid， and strong durability. However， due to the low relative motion speed between the permanent magnet and the conductor plate， its energy dissipation efficiency is not high， which limits its application in engineering. To enhance the performance of traditional composite tube eddy current dampers， a composite tube eddy current torque damper with the optimized magnetic circuit is proposed in this paper. Compared with traditional composite tube eddy current dampers， the damper proposed in this paper has litter magnetic leakage and a smaller installation volume. In addition， the working speed of the damper is increased by adding a gear accelerating device to further improve the energy consumption performance. The finite element model of the eddy current torque damper was established based on COMSOL analysis software， and the effects of air gap， conductor tube thickness， and back iron thickness on the torsional damping coefficient were analyzed. At the same time， considering the installation space size， the formula for calculating the eddy current damping force is derived， and the formula for estimating the eddy current torque damping coefficient of the composite pipe is proposed. The prototype of a large speed discharge eddy current torque damper and the principle verification device of the expansion mechanism are manufactured， and the impact retarding performance is tested. The results show that for the specific damper parameters， reasonable values of the thickness of the permanent magnet and conductor plate can obtain high torsional damping coefficients. The damping coefficient estimation method presented in this paper can accurately describe the mechanical properties of a velocity amplifier eddy current torque damper in the damping linear section. Using a prototype damper weighing about 12 kg， the final kinetic energy dissipation efficiency of the test development mechanism can reach 41.6% under the most unfavorable working conditions， which has a strong energy dissipation efficiency advantage.