The work aims to achieve highly efficient and precise heat sealing and cutting of the film in the heat shrink packaging process of large or multi-items, and deign, analyze and optimize a heat sealing and cutting device. Based on the double film wrapping, heat sealing and cutting process requirements, from the perspective of mechanical design, combined with the actual production, the mechanical structure was designed and the motion simulation and structural optimization were conducted. Through the simulation analysis, it was confirmed that the process of "first sealing and then cutting" was realized between the cutter and the heat sealing plate. The duration of the heat sealing and cutting process was about 1 s, the working pressure between the heat sealing plates was about 250 N, and the overall working performance of the device was good. The device is designed reasonably, and it works stably and accurately. It can achieve the heat sealing and cutting function for heat shrink packaging.