A novel winding loss model of Flyback transformer for loss calculation is proposed. With this model, the winding losses can be divided into transformer loss and inductor loss by decomposing the total winding currents into two components, that is, transformer current, or T-component and inductor current, or L-component, which are orthogonal in continued conduct mode (CCM). Although the orthogonal feature is lost in discontinued conduct mode (DCM), the winding loss can also be achieved by the introduction of equivalent frequency. The model has been verified by FEA simulation. Since the winding losses of Flyback transformer can be considered as the sum of transformer loss and inductor loss individually, the total winding losses of Flyback transformer will be obtained by ID eddy current analytical model.