To solve the interference and collision problem of industrial robots in assembly tasks, an accurate collision detection method for robot array assembly based on digital twins is proposed. According to the proposed digital twin system framework, the digital twin model of industrial robots is constructed to realize the real-time mapping between the physical equipment layer and the virtual model layer, the joint angle prediction model based on multi-layer perceptron predicts the future joint angle of industrial robots, and the proposed collision detection method based on hybrid hierarchical bounding box makes up for the lack of collision detection in Unity3D. The collision problem that may occur in the assembly process of the robot is avoided. The results show that the digital twin system is feasible and effective.