Coal seams in China have many features，such as low permeability，high gas pressure and large gas content，so it is extremely difficult to extract gas from the original coal seam.The permeability has to be increased in order to improve the efficiency of extracting gas and shorten the time of extracting gas in advance.Among many technologies of increasing the permeability by cracking coal rocks，liquid CO2 can not only contribute to the increase of permeability，but also substitute for gas，which can improve the efficiency of extracting gas significantly.In order to explore the application and effect of the L-CO2 fracturing technology in high gassy and low permeability coal seams，a self-developed high voltage pulse discharge excitation supercritical CO2 test device is used.The complex process of electric,thermal and force coupling in liquid CO2 phase transformation induced by high voltage pulse discharge is quantitatively studied,and the dynamic response law in the supercritical state during the process is determined.According to the Span&Wagner equation state of CO2,the energy needed for liquid CO2 to supercritical CO2 gasification is analyzed and calculated,and the results show that the pressure of the supercritical CO2 will reach 11 MPa,18 MPa and 26 MPa respectively under the condition that the discharge energy in the reactor reaches 20 kJ,40 kJ and 60 kJ.The pressure of supercritical CO2 in the reactor is monitored by adjusting the initiation voltage level to 1500 V,2000 V and 2500 V respectively,and discharge energy of 20 kJ,40 kJ and 50 kJ respectively.The relation curve between pressure and time is then obtained,and the changing rule of the pressure curve is analyzed.The results show that the degree of liquid CO2 gasification is different under varying amounts of discharge energy,and the supercritical CO2 pressure in the reactor increases with the increase of discharge energy.The research results provide a reference for the application of anti-reflection technology of continuous and repeated cracking of coal seam under high pressure discharge excitation of supercritical CO2.