Abstract: In this paper, the method and key elements of the 70 m antenna structure preservation design for the first Mars exploration are introduced in detail. The umbrella-like support structure is used to realize the equal stiffness support of the reflector, so as to achieve the effect of uniform deformation of the structure, improve the anastomosing accuracy of the main reflector, and lay a solid foundation for the preservation design. Three degrees of freedom adjusting mechanism is used to realize the effect of the secondary reflector following control, compensate the best fit of the main reflector and the electrical performance decline caused by the deformation of the secondary support structure, and provide a strong guarantee for the shape preservation design. The design concepts of equal stiffness used in this project are rare design concepts in China and have reference significance for later large-aperture antenna design in our country. The three degree of freedom adjusting mechanism can effectively compensate the electrical performance degradation caused by the deformation of the auxiliary support structure and the adjustment of the focus position after the best fit of the main reflector.