The invention is suitable for the technical field of the transformer, and provides a detection method and device of transformer iron core DC magnetic biasing. The method comprises the following steps:collecting a vibration signal at a tank body surface of a transformer; performing Fourier conversion processing on the vibration signal to acquire fundamental wave and harmonic wave of the vibrationsignal; computing an odd harmonic fundamental frequency ratio of the vibration signal according to the fundamental wave and the harmonic wave; and detecting the transformer iron core DC magnetic biasing degree according to the odd harmonic fundamental frequency ratio. Through the method disclosed by the invention, the problem whether the transformer causes the DC magnetic biasing cannot be judgedthrough the vibration of the transformer body and the problem about the caused DC magnetic biasing degree are solved.