Abstract: In order to study the influence of surfactant on the pore structure of coal, the treatment of coal samples with different concentrations of twelve sodium sulfonate solution was carried out. The results show that the average pore size of coal sample treated with surfactant decreases gradually; the total specific surface area of coal samples treated with surfactant decreases, and it has power function relation with surfactant concentration, the specific surface area of the micropore decreases and the specific surface area of middle holes and transition holes increases; the total pore volume of the coal sample treated with surfactant also decreases, and both of them conform to the power function relation, and the pore volume proportion under each pore diameter does not change significantly; the fractal dimension of coal sample after surfactant treatment increases, and the two agree with power function.