The invention relates to a method for suppressing direct current magnetic biasing of a transformer. An apparatus capable of suppressing direct current of a neutral point of the transformer is connected to the neutral point of the transformer; and conversion between a direct grounding operation state and a capacitor grounding operation state is realized by a switch connected with a capacitor in parallel. The direct current of the neutral point of the transformer can be suppressed effectively, safe and stable operation of the power transformer with direct current magnetic biasing can be ensured, and equipment accident caused by direct current magnetic biasing can be prevented; in addition, when the system suffers from a failure, a bypass protection blocking capacitor can be switched rapidly, so that adverse influence to the insulativity of the neutral point of the main transformer can be avoided, and safe and reliable operation of the transformer is ensured.