The invention provides a method and device for preventing non-fault phase saturated differential protection maloperation. Under the conditions that a certain phase meets a differential protection starting judging condition and a differential protection relay meets the action, the occurrence of in-region fault of a certain phase is primarily judged; on the premise of generating the in-region fault,then the differential current of the phase generating the fault and a maximum phase braking current meet braking relationship or not is judged; if the braking relationship is not met or the fault isprimarily judged to be an out-of-region fault, whether the current phase meets a braking current CT saturation criterion or not is continuously judged; if the CT saturation criterion is not met, the fault is determined to belong to the out-of-region fault; at the moment, the current phase differential protection is locked; the saturation feature differential protection maloperation of the non-fault phase due to secondary loop reasons can be effectively avoided, so that the reliability of the protection device is improved.