The present invention relates to a judgment method of direct-current magnetic bias in a 110kV three-phase five-column autotransformer. Equivalence is realized according to the magnetic flux conservation principle under the same input current, the direct current of the neutral point of the 110kV three-phase five-column autotransformer and the direct current of the neutral point of a transformer of a next voltage level are acquired; when the neutral point of the 110kV three-phase five-column autotransformer is switched to a direct current blocking device, direct current passing through each phase of winding of the 110kV three-phase five-column autotransformer can be obtained equivalently according to the magnetic flux conservation principle; and whether the direct current passing through each phase of winding of the 110kV three-phase five-column autotransformer exceeds standards is judged. According to the method of the invention, modeling is performed on the 110kV three-phase five-column autotransformer; equivalence is realized based on the magnetic flux conservation principle under the same input current; and therefore, measurement problems of the direct current in the series-connected windings of the autotransformer after the neutral point of the 110kV three-phase five-column autotransformer is switched to the direct current blocking capacitor can be solved, and a guarantee can be provided for the reliability of the normal operation of the 110kV three-phase five-column autotransformer which needs to withstand direct-current magnetic bias.