Abstract: The experimental apparatus for the sorption and desorption of coal gas under high-voltage inverter and frequency electric field was developed. The physico-chemical property was analysed by taking 3^# coal as research object. In the condition of 0-4 MPa experimental pressure, 2 000 V electric voltage, 10 kHz and 40 kHz frequency, the sorption and desorption of 3^# coal was studied. The result is that the gas desorption isotherm line submits to Langmuir law under high-voltage inverter and frequency electric field. With the increment of the experimental pressure, the gas desorpted quantity increased in exponent law. The gas desorpted quantity of 40 kHz is more than the result of 10 kHz.