The invention provides an obtaining method of a direct current magnetic biasing hysteresis loop of a transformer core material, relates to measurement of the hysteresis loop, and has the following steps of manufacturing a device used by the method by using a variable-voltage transformer, a transformer core model, a direct current source, a digital oscilloscope, a power analyzer and a power frequency alternating current power supply, and obtaining any given alternating current working point in the scope of 27 V-486V by using the device according to 13 steps, namely the biasing hysteresis loop of the transformer core material to be measured under the effect of any given direct current magnetic biasing magnetic field intensity in the scope of voltage Ug output by the power frequency alternating current power supply and in the scope of 0.1 A-2A. The obtaining method adopts the mode of alternating current and direct current series connection stimulation same with that when an actual transformer generates direct current magnetic biasing, simulates direct current magnetic flow in an overlapping iron core material under working conditions of the direct current magnetic biasing, and completely meets actual situations when the power transformer has the direct current magnetic biasing. Obtained direct current magnetic biasing hysteresis loop of the transformer core material is close to the true value.