The invention provides a BIM-based steel structure engineering real-time monitoring and early warning method. The system comprises a BIM model processing subsystem, a structure analysis and service center subsystem, a communication network subsystem and a data acquisition equipment terminal. Based on a building structure finite element model based on a BIM data model and real-time sensor data provided by a data network, the structure is accurately simulated and analyzed, any existing or potential structure problems are judged, early warning information is sent out, and problem components are clearly identified in the BIM model through different colors; meanwhile, structural deformation data, external environment data and the like transmitted by the equipment terminal are collected and automatically added to the BIM informatization model, and the model is synchronously adjusted and changed according to structural deformation. According to the invention, high-precision steel structure engineering health monitoring is realized, and the authenticity of structure monitoring and the accuracy of risk analysis are improved through continuous self-adjustment of the BIM model.