In order to solve the problems of assembly workshop, such as the uncertainty of personnel location, the delay of equipment information collection and the decentralization of environmental data management, a real-time monitoring method of assembly workshop resources based on digital twin was proposed. The connotation and composition of each level of the assembly workshop digital twin model are analyzed, and the technical framework of the five-level digital twin model is established; On this basis, the description and characterization of key production resources in assembly workshop, the online monitoring of personnel based on short-distance wireless signal strength superposition, the monitoring index system of assembly workshop and the implementation of online real-time monitoring are described in detail, and the real-time monitoring system is designed and developed. The results of an example show that the method realizes the real-time and dynamic monitoring of all kinds of resources in the assembly workshop, and is effective.