Abstract: To promote the application of quadrupole electromagnetic orbital launcher in ground-to-air missile launching, the interference structure of quadrupole armature was studied. On the basis of finite element software ANSYS Workbench and its 3D interference fit simulation, with four evaluation indexes-maximum equivalent stress, coefficient of contact area, uniformity coefficient of contact pressure and coefficient of relative contact pressure-selected to describe the contact characteristics, the four interference structure parameters of quadrupole armature (interference amount and length, tail width and thickness) were optimized comprehensively by orthogonal experiment. The results show that the optimal combination of 2 mm interference amount, 140 mm tail width, 40 mm tail thickness and 270 mm interference length can make the contact characteristics between armature and rail ideal in the early stage of launch, which can be used as a reference for the design of quadrupole armature structure.