The invention provides an electrolyte tank group ground insulation resistor detection method and an electrolyte tank group ground insulation resistor detection device. According to the ground insulation resistance detection method of the electrolyte tank group of the prior art, an universal instrument is directly used for detection, and then the technical problems such as the damaging of the universal instrument or the large measurement errors are caused by the high voltage, the large strong current, and the high intensity magnetic field of the electrolytic tank group. The above mentioned technical problems of the prior art are solved by using the detection method and the detection device provided by the invention. By adopting the detection method and the detection device provided by the invention, a testing resistor, the resistance value of which is given, is connected with the electrolytic tank group, and the voltage of the whole segment or the voltage between partial segments of the electrolytic tank group can be tested, and at the same time, the voltages of the two ends of the testing resistor are tested, and then the ground insulation resistor of the electrolytic tank group is acquired by adopting the Ohm law, and the technical effect of the electrolytic tank group of detecting the resistance value of the ground insulation resistor is acquired by lossless measurement of related data of a testing circuit.