In existing IFC standard systems， there is a problem of not being able to express the unique characteristics of type-form， structure， attributes， and art in Chinese historic buildings. This paper constructs the semantic relationship diagram of bracket sets， mortise， and tenon structures based on the UML. According to the IFC four-layer frame system， the extension of corresponding component entities， relationship entities， and property sets is achieved through entity extension and property set extension. This extension is carried out in a layered manner， and the extended content is described using EXPRESS. Model files are parsed and edited using the IfcOpenShell toolkit and VScode； Solibri and Blender are used as validation platforms to verify the visualization， readability， and content of entity and attribute set information of IFC files. According to the verification results， the extension of the historic building domain proposed in this paper conforms to the extended system method of IFC， which is of great significance to realize the interaction and sharing of the structure and art characteristics of historic buildings in the information model， and can provide strong support for the information protection of historic building engineering investigation， repair， and operation-maintenance.