Abstract: The conventional method for polarity verification of current transformers with multiple windings primarily involves applying DC current to the primary side and observing the deflection direction of milliammeter pointers on secondary windings to determine polarity. However, this approach exhibits limited accuracy due to electromagnetic interference. To address this, a portable automatic polarity verification device for current transformers with multiple windings has been developed. The system employs a secondary current detector and analyzer to capture secondary current signals, decomposes them into different scale coefficients through discrete wavelet transform, and reconstructs signals via inverse transformation to mitigate electromagnetic interference. A Sigmoid function is utilized to model the relationship between current alarm signal conditions and effective bus voltage values, with parameters determined through least squares fitting. The central point of the fitted function reflects sensitive voltage thresholds, while confidence intervals quantify uncertainty ranges. By extracting fundamental frequency components and calculating ratio and phase differences, the system verifies polarity. The host's signal acquisition module processes data, with PLC modules performing computational verification of polarity, controlling auxiliary devices, and displaying results through display/alarm modules. Experimental validation demonstrated that the proposed method achieves an average correlation coefficient of 0.94 for multiple winding polarities, demonstrating optimal verification performance.