Abstract: Aiming at the demolding difficulty in sealing ring mounting groove buckle on both ends inside the product, a rotary demolding mechanism with three-time ejection was design in this paper, and a dynamic mathematic model for this mechanism was constructed. Based on this mathematical model, the template driven mechanism for realizing the rotary demolding of the sealing ring mounting groove buckle was confirmed to be entirely feasible. Moreover, a slider displacement control mechanism with three-order ejection was designed according to the requirement of demolding mechanism. This mold had two plates, one module and two cavities, and three-side gate runner ejection plate structure. The demolding mechanism, top-out sequence control mechanism and die structure designed in this paper can provide a useful reference for the mold design of similar products.