In view of the fact that the criterion of sweep impedance method in transformer winding deformation detection is not clear and depends on the experience of personnel. Fundamental characteristics of sweep frequency impedance spectroscopy are combined, an intelligent winding deformation detection technology based on sweep impedance spectrum identification is proposed, the phase zero crossing point of impedance amplitude, 70 °phase characteristic frequency point, extreme value point and related parameters are used as characteristic parameters, the statistical analysis of each parameter under different fault states is carried out to verify the effectiveness of the characteristic parameters of sweep impedance spectrum in detecting transformer winding deformation. As the result, it was shown that the selected characteristic parameter of sweep impedance spectrum can well identify the deformation or failure type of the winding. This study provides a reference for the development of winding deformation fault detection of power transformers in China.