How to predict and control the micro-assembly interface fusion adhesion debonding and peeling characteristics accurately is a key scientific and technical problem in the preparation of high-performance micro-mechanical motion in polymer in-mold micro-assembly. Aiming at this key scientific and technical problem, the simulation platform of the in-mold micro-assembly micro-mechanical motion interface fusion adhesion debonding and peeling behavior was constructed, and the relationship among injection temperature-debonding and peeling fracture toughness parameters of material pair interface-interfacial fusion adhesion debonding and peeling characteristics was built. The research shows that the crack initiation stress, critical strain energy release rate and the driving force of complete debonding and stripping in the micro assembly interface are positively correlated with the injection temperature of the secondary molding melt. The reduction of the secondary molding injection temperature can significantly reduce the crack initiation stress, critical strain energy release rate in the micro assembly interface, and inhibit the fusion adhesion of the micro-assembly interface, which is beneficial to reduce the debonding and peeling driving force of the micro-assembly interface fusion adhesion, and improve the movable performance of the micro-assembly interface.