A new type of rotary points cover device for sealing machine was introduced in this paper. First, its structure and working principle were analyzed in detail through the introduction of the motion of covers separation. Then the cutter design was carried out and the key parameters were determined, and finally, motion simulation was performed for the device to prove whether it met the design requirements. Though simulation analysis, the breakthrough point of the upper and lower cutter edges always had a distance of about 10° in the process of covers separation, which conformed to the cutter shape, and the function of covers separation could be successfully achieved. The device was characterized by good stability and simple structure, and it met the design requirements as proved by actual using.