In remote diagnosis center of power transmission and transformation equipment, condition monitoring data needs to be integrated and a unified information model is required. The information model scope and the modeling principle and method are firstly proposed. Then a foundation model are tailored based on IEC TC57 common information model. Additional models such as monitoring point model, equipment test report model, defect report model, environment monitoring model, some power system resource classes and technical parameters of assets are supplemented to the foundation model to make the comprehensive model to support diagnosis platform building and data analysis. The unified condition monitoring information model researched has been used in the construction of the remote diagnosis center.