It is necessary for electronic transformer to make calibration before putting it into practice. To solve the problems in actual calibration process, a novel electronic transformer calibrator is designed. In principle, this system adopts both the direct method and the difference method, which are two popular methods for electronic transformer calibration, by this way the application of the system is extended with its reliability improved. In the system design, based on virtual instrument technology, LabVIEW and WinPCap toolkit are used to develop the application software, and it is able to calibrate those electronic transformers following the standard of IEC 61850. In the calculation of ratio and phase error based on fast Fourier transform, a new window function is introduced, and thus the accuracy of calibration, influenced by the frequency vibration, is improved. This research provides theoretic support and practical reference to the development of intelligent calibrator for electronic transformers. DOI: http://dx.doi.org/10.11591/telkomnika.v11i3.232