Coal rock desorption testing method

The invention relates to a coal rock desorption testing method. The coal rock desorption testing method comprises the following steps of: (1) adding a certain amount of coal rock particles with determined diameters in space between two filter screens in a desorption reaction vessel, and injecting methane gas in the desorption reaction vessel so that methane molecules is adsorbed by the coal rock particles; (2) closing a check valve of a methane gas tank, initializing the pressure of a return pressure valve, and measuring the water outlet quantity of a measuring container by a precision electronic balance; and (3) adjusting the return pressure valve until return pressure is 0MPa, and then measuring dry coal rock desorption quantity and desorption rate under different pressures without liquid influence. Coal rock particle samples are placed in circulating water at different temperatures, under different pressures and with different rotating speeds, so that the desorption law of methane in the coal rock particles under the influence of liquid and the desorption quantity and the desorption rate of the methane in the coal rock particles in liquid environments under different air pressures are analyzed, and the accuracy of acquired data is high.