The invention relates to the field of power system electric leakage protection, in particular to a digital signal processing (DSP)-based current separation motion type electric leakage protection device and a DSP-based current separation motion type electric leakage protection method. The device comprises a detection unit, an analog to digital (A/D) conversion unit, a DSP unit and an execution unit. In spite of a phase relation between electric shock / electric leakage current and normal residual current and in spite of the variation of a total residual current amplitude after electric shock, an effective value of the electric shock / electric leakage current can be accurately detected. The invention has the ideal protection operation characteristics and is particularly applicable to full-network main protection and large-branch protection of lines of a three-phase four-wire system of a low-voltage power distribution network.