Abstract: Based on the uniform distribution of gas in the adsorption drying unit, a mathematical model was established by using the relevant theory of fluid mechanics.The gas distribution system of low concentration coalbed methane adsorption drying unit was studied by numerical simulation, and the optimization method of gas distribution system in adsorption tower was put forward.Through calculation, it is found that for the cylindrical drying tower in practical application, due to the poor structure design of the connection between the intake pipe and the tower body, the uneven distribution of axial airflow is very serious, and the absolute non-uniformity coefficient of gas flow velocity is 1.028; if the orifice plate type gas distribution system is installed in the adsorption tower, and the holes on the baffle plate are arranged as a whole, with the same aperture of 3.0 mm, the absolute non-uniformity coefficient of gas flow velocity decreases from 1.028 to 0.321, and the uniformity is improved; the aperture of the baffle center of the air distribution system is reduced to 1.5 mm, and the aperture near the wall surface is increased to 4.5 mm, when the holes are arranged in an equilateral triangle, the absolute non-uniformity coefficient of gas flow velocity is further reduced to 0.101, and the flow is more evenly distributed.