Abstract: In this paper, the electrochemical modification of lean coal samples with potential gradients of 1 V/cm, 2 V/cm and 4 V/cm, gas adsorption desorption test of coal samples before and after modification, and the change of pore structure and surface group of coal samples before and after modification were analyzed by low temperature liquid nitrogen adsorption test and infrared spectrum test. The results show that: the saturated adsorption capacity of unmodified lean coal sample is 30.030 mL/g, the Langmuir pressure of unmodified lean coal sample is 0.876 MPa, the final desorption rate of unmodified lean coal sample is 83.204%. After electrochemical modification with potential gradients of 1 V/cm, 2 V/cm and 4 V/cm, the saturated adsorption capacity of coal sample is 29.239 mL/g, 28.329 mL/g and 26.667 mL/g,and the Langmuir pressure of coal sample is 0.932 MPa, 1.042 MPa and 1.048 MPa respectively,the final desorption rate of coal sample is 84.235%, 85.541% and 87.840% respectively; the larger the potential gradient, the smaller the specific surface area of the modified coal sample, the larger the average pore diameter, and the more the number of oxygen-containing functional groups, the better the effect of inhibiting gas adsorption and enhancing gas desorption.