The invention relates to a piezoelectric self-excited impulse-type micro electro discharge machining device, comprising a linear motion axis, an actuator and electrodes, wherein the linear motion axis is connected with one end of the actuator; the other end of the actuator is connected with the electrodes; an equivalent RC circuit is constituted by the actuator, a direct current electrical source, a capacitor, a resistor R1 and a resistor R2; the two poles of the direct current electrical source are respectively connected with the electrodes and the workpieces; the two poles of the direct current electrical source are also respectively connected to the two ends of the piezoelectric ceramics of the actuator. The invention also discloses a machining method by utilizing the device. In the invention, pulse discharge is generated by the self-excited vibration of the actuator by combining the direct current electrical source and the actuator; and in the machining process, the adaptive vibration of the electrode improves the discharge of electric corrosion products and obviously improves the machining efficiency and quality.