The invention provides a sequence differential current-based zero sequence current differential protection phase selection method and device. The method comprises the following steps: a three phase differential current and a sequence component of the three phase differential current are calculated, and a zero sequence current differential protection phase selection device acts. The device comprises a collecting unit, a calculating unit, a criterion determining unit and a zero sequence current differential protection phase selection device. According to the zero sequence current differential protection phase selection method and device, when a single-phase grounding fault occurs in an electric power transmission line, characteristics of positive, negative and zero sequence differential currents at a fault point can be used for recognizing a fault phase of the single-phase grounding fault because the negative and zero sequence differential currents at the fault point are the same in magnitude and direction when the single-phase grounding fault occurs; the zero sequence current differential protection phase selection device cannot be affected by any load current and can be used for correctly picking out the fault phase even when a single-phase high resistance grounding fault occurs; the zero sequence current differential protection phase selection device can be used in cooperation with zero sequence current differential protection, a selected zero sequence current differential protection phase can trip when the single-phase high resistance grounding fault occurs in the electric power transmission line, and a phenomenon that three phases trip when a minor fault occurs can be prevented.