Abstract: In order to study the effect of electric field on methane adsorption capacity of coal and the adsorption constants a & b, we adopted the DC pulse power to carry out this study by changing the frequency of DC pulse electric field. The result shows that the methane adsorption capacity of coal still follows the Langmuir isotherm adsorption curves under the influence of the external DC pulse electric field; DC pulse electric field can inhibit methane adsorption characteristics of coal, the increasing of electric field frequency, the methane adsorption amount of coal declines; DC pulse electric field reduces the specific surface area of coal which weakens the methane adsorption amount of coal; meanwhile the adsorption constant of coal, namely b reduces as the DC pulse electric field frequency increases and there is a negative index relation between them and the adsorption constant a remains basically unchanged.