Abstract: A method of recovering voltage of a primary cell and its device. The method of steps of reading a cell to obtain start voltage, capacitance and number of the cells to be recovered, of imposing sine curve impulse once every 1-3 second on the positive pole of the cell(s) for stimulating chemical substance in the cell(s), of imposing sine curve impulse once every 5-7 seconds when the voltage recovery reaches 70%, of imposing sine curve impulse once every 10-12 seconds when the voltage recovery reaches more than 90%, and of changing sine curve impulse into a small stream of impulse when the voltage recovery reaches more than 99% for stabilizing the chemical substance in the cell(s). The device includes a reading circuit, a stimulating circuit, a control circuit, a control circuit and a voltage transforming and rectifying circuit.