For conceptual analysis of the principle of relay vibration protection, this article establishes the simulation system model of directional current protection in MATLAB/Simulink environment through the protection algorithm. Various outcomes have been achieved for the proposed approach during the faulty conditions. The outcomes obtained during the fault period reveals that the waveform of three-phase current changes greatly, and the amplitude of three-phase current at power supply side increases sharply. After 0.02s signal acquisition and processing, the action signal acts after 0.07s, and the fault is removed. In case of two-phase short-circuit, two-phase grounding short-circuit and other faults, the fault can be removed smoothly after signal acquisition and processing. In this paper, the directional current protection simulation system based on microcomputer protection model is built, and the changes of voltage, current and action signal are demonstrated through GUI interface, and analyzed and verified.