Based on analyzing structure and characteristic of flying capacitor inverter, in order to diagnose parametric fault of inverter. With global analytical redundancy relation method based on bond graph model carry out detection and localization of the parametric fault. According to bond graph theory established the bond graph model of flying capacitor inverter, through the way of adding observation signal and virtual sensor to bond graph model to establish the diagnosis bond graph model of system, thus getting the global analytical redundancy relation of system. Finally, using 20-sim simulation platform to simulation and analysis, and verifying the global analytical redundancy relationship based on bond graph model is feasible in the aspect of parametric fault diagnosis.