The invention relates to a measuring method for the remanence of a transformer iron core. The method comprises the steps that 1) the magnetization curve of the transformer iron core is acquired, wherein the magnetization curve reveals the relationship between the direct current component of no-load current and the remanence of the iron core; 2) 380V alternating current test voltage is applied to a transformer winding, and the no-load current is measured; 3) the direct current component of the no-load current is acquired; and 4) the iron core remanence is acquired according to the magnetization curve and the direct current component. Compared with the prior art, the measuring method provided by invention has the advantages that the method is simple and feasible, can quantitatively measure the remanence of the main transformer iron core, and guides the development of the degaussing scheme of the remanence of the main transformer iron core; the degaussing effect is evaluated; and a technical support is provided for the test and operation of a main transformer.