The work aims to design an automatic waist sealing mechanism for socks in view of the problems of low efficiency and uneven quality in artificial waist sealing of socks. Based on the functional requirements of waist sealing of socks and the modular idea, the key device of the sock waist sealing mechanism was designed to realize the functions of paper card taking and placing, horizontal and vertical folding, sticking, etc. The three-dimensional model of each module was established by Solidworks, and virtual assembly was carried out. The motion plug-in of Solidworks was used to carry out the dynamic simulation analysis on the transverse folding device, and the mechanical model of the key parts of the waist sealing mechanism was established and the finite element analysis was carried out by the simulation toolbox of Solidworks and MATLAB. The motion performance of the waist sealing mechanism was analyzed by comparing the artificial waist sealing mechanism. The design of each device was reasonable. The motion analysis showed that the origami interval between 0.1 s and 0.6 s could meet the motion function requirements, the key parts of the sock waist sealing mechanism could meet the mechanical requirements and the performance of waist sealing mechanism could meet the requirements of sock enterprises. The designed automatic waist sealing mechanism of socks has reasonable structure and meets the requirements of the waist sealing function, which provides a feasible solution for automatic waist sealing and packaging of socks.