The invention provided a vertical base of a mutual inductor. The vertical base comprises a location beam, a positioning beam is located on the location beam, center positions of the location beam and the positioning beam are connected, and an included angle with a preset angle is formed between central lines. A first groove and a second groove are respectively arranged at two ends of the location beam, a first bolt is arranged in the first groove, a second bolt is arranged in the second groove, a third groove and a fourth groove are respectively arranged at two ends of the positioning beam, a third bolt is arranged in the third groove, a fourth bolt is arranged in the fourth groove, and the first bolt, the second bolt, the third bolt and the fourth bolt are respectively matched with four installation holes of the mutual inductor. The vertical base of the mutual inductor enables the mutual inductor to be fixedly connected onto the vertical base through four grooves and four bolts corresponding to the four grooves. The location beam and the positioning beam form a cross-shaped structure, stability is high, the mutual inductor can be vertical, workers of a transformer substation can conveniently test the mutual inductor inside the transformer substation, time is saved, and test efficiency is improved.