Orientation jetting and fracturing exploitation method for coal bed gas under coal mine

The invention discloses an orientation jetting and fracturing exploitation method for coal bed gas under a coal mine. The method includes the steps that a drilled hole along a coal bed is formed in a top plate or a bottom plate; a fracturing pipe set and a radial perforator are placed in a first perforation position; the hole is sealed; the fracturing pump set and the perforator are connected with corresponding pump sets respectively, and a jet flow channel is formed by the perforator and used for communicating the coal bed and the drilled hole; annular fracturing liquid is injected into the drilled hole in a pressure mode, and meanwhile annular pressure is kept; the coal bed is continuously jetted for preset time so that cracks can be formed on coal bodies and extend in the bottom direction of jetting holes of the coal bed; jetting and fracturing are stopped at the same time, the perforator is moved to a next jetting position to form the jet flow channel, and then fracturing liquid is pressurize and jetted continuously; the steps of independently jetting a rock stratum and pressurizing and jetting the coal bed are repeatedly executed until jetting and fracturing at all positions in the drilled hole is finished, and then the coal bed gas is extracted. The orientation jetting and fracturing exploitation method has the advantages that the trend and the quantity of the cracks are controllable, exploitation efficiency of the coal bed is high, the gas disaster of the mine can be effectively prevented and treated, and economic and social benefits can be improved.