The invention discloses a coal bed gas fracturing method, and belongs to the field of coal bed gas development. The method includes the steps that 1 perforation is carried out in the middle section of a coal bed; 2 low-viscosity fracturing liquid is prepared; 3 fracturing sanding is carried out at least three times at the perforation position with the fracturing liquid, and after each time of fracturing sanding, a pump is shut down for 30-60 min, and then fracturing sanding of the next time is carried out. Through perforation in the middle section of the coal bed, an overflowing channel of the fracturing liquid is controlled in the middle section of the coal bed, and pressure channeling risks of the prepad liquid injection stage in the fracturing process are avoided; cracks are controlled to extend in the coal bed by conducting fracturing sanding at least three times, a supporting agent is effectively laid in the coal bed to form the long and high channel with high flow guide capacity, and the coal bed gas yield is increased.