Abstract: Human-computer interaction is an essential characteristic and a technical bottleneck of virtual assembly. The construction of an assembly model that can reflect the process of interaction is a critical problem in virtual assembly research area. In this paper, a temporal assembly model is put forward, and stringent definitions and analysis of temporal aggregation relationship, temporal constraint dependence relationship and temporal behavior segment are given. In order to realize this temporal model, an intermediate model of part and object complex behavior mechanism in virtual assembly are given, and at the same time, formal description of direct manipulation interaction process, interaction mode and assembly process knowledge is also given. These are bridges between interaction and assembly model and also between assembly model and assembly process output. Uniform express model can reduce redundancy of assembly information, increase reuse of interaction information, and is a new method of assembly process planning creation.