The invention relates to a method for checking voltage transformer change and voltage loop wiring correctness by using a transformer turn ratio & group tester. The method comprises the following steps: (1) checking the grounding and voltage loops of three single-phase grounding type voltage transformers, (2) using a transformer turn ratio & group tester to check the change of primary and secondary main windings of the three single-phase grounding type voltage transformers and system voltage loop wiring, (3) checking the change of primary and secondary assisted windings of the three single-phase grounding type voltage transformers and zero sequence voltage loop wiring and removing all temporary test lines. According to the method, the transformer turn ratio & group tester is used to check the change of three single voltage transformers in Y0/y0/delta wiring and the voltage loop wiring, and the voltage transformer turn ratio, the lead wire phase sequence, the phase and the grounding correctness of different connection group windings can be ensured.