Given the development trend of power transformers with high voltage and high capacity, the stray loss and local overheating problems caused by the eddy-current pose a serious threat to the stable operation of power systems. making the accurate calculation of the eddy-current field become a key requirement to ensure the safe and efficient operation of power systems. In this paper, we propose a new method of This study focuses on the three-dimensional eddy-current field calculation of transformers. Based on the basic equations of eddy-current field, derived the calculation formula for the three-dimensional eddy-current field edge element and implemented it through programming, and the results of the self-programmed calculation are compared with those of the commercial software by taking the single-phase four-column transformer and the TEAMP21-B as the validation objects. The results show that they are basically consistent. The research results provide an effective calculation method and data support for the design optimization and performance improvement of transformers.