The invention relates to a transverse differential protection method of a neutral point of an electric furnace transformer. In the method, the influence of the longitudinal differential protection of a compensating capacitor is comprehensively considered, and when the compensating capacitor is shorted out within the longitudinal differential protection range, the rapid exit of the transverse differential protection of the electric furnace transformer is latched, and a time delay exist of transverse differential protection is used as the back-up protection of the longitudinal differential protection of the capacitor, and thus, the transverse differential protection can be accurately actuated according to the type of a fault to protect the electric furnace transformer so as to prevent the electric furnace transformer from being burnt up.