The invention discloses a method for inhibiting ferroresonance. The method comprises the following steps of: (1) inferring the occurrence range and working condition of the ferroresonance of a voltage transformer by an EMTP analytical method: the smaller the capacitor of a GIS bus over the ground, the bigger the probability of the ferroresonance, wherein the working condition is intra-string T zone of 3/2 wiring or 4/3 wiring, at this time a circuit breaker is in a separating brake state, the capacitor of the bus over the ground is small, and an intra-string voltage mutual inductor will have the ferroresonance; (2) determining the excitation characteristic and coil internal resistance parameter of a saturable reactor; and (3) connecting the two connecting terminals of the saturable reactor which meets parameter condition with a secondary winding of the voltage transformer. The method can avoid VT heating damage and equipment damage accident due to the ferroresonance in a GIS power station effectively, eliminates the potential safety hazard of the possible ferroresonance in a power network system, and plays an important role in guaranteeing the safe operation of the power network; and therefore important social and economic benefits are generated.