Based on the development of existing transformer harmonic models at home and abroad and the limitations of their applicable scopes, a model of harmonic loss for windings is established for the purpose of accurately quantifying harmonic losses of transformer windings. This model comprehensively considers the influence of the skin effect and the proximity effect on the windings under harmonic conditions and analyzes the distortion characteristics of the winding resistance parameters based on the principle of electromagnetic field. The experiment for measuring winding resistance under each harmonic current is performed. Comparing with the experimental measurement values, the traditional model calculation values and the calculated values of the model, it is proved that the model improves the calculation accuracy and makes loss calculation of the transformer winding more accurate. Finally, based on the experimental measurements values, an engineering practical model of harmonic resistance of transformer winding is established, which has certain guiding value for engineering calculation. This work is supported by Key Projects of National Key Research and Development Program of China (No. 2016YFB0101900).