The formalistic description about classification of information is an important and difficult point in information integration currently. The factor expression theory based on knowledge can describe the relationship between concepts, and also can describe the concept’s semantics through this relationship. This method has uniform frame of knowledge description and strict mathematical theory foundation. This research puts forward the architecture model of equipment total system and life cycle information, and the knowledge expression theory based on factor describes the classification of equipment information. With the basic information of equipment, it also proves that the method is valid in the equipment information integration. Therefore, it can provide theory support for resolving the semantically heterogeneous problem in the information integration of equipment field.