The utility model provides a drill bit for soft coal bed gas extraction drill protection of an underground coal mine, and belongs to drill bits for drill protecting pipe penetrating. Three centrosymmetric cutting main wings are arranged outside a drill bit body, a slagging concave surface is arranged between every two cutting main wings, and each slagging concave surface is provided with a slagging air hole; the center of the drill bit body is an unidiameter inner hole, the top end of the inner hole is lower than the cutting main wings, an inclined table top is arranged between the hole port of the inner hole and each slagging concave surface, each inclined concave surface is provided with a tooth piece groove and a pin column groove, and each tooth piece groove vertically intersects the corresponding pin column groove in the horizontal plane; one tooth piece close to the inner hole side is suspended, the back surface of the tooth piece is provided with a polycrystalline diamond composite piece, and the bottom surface of the tooth piece is provided with a magnetic block; one tooth piece far away from the inner hole side is fixed in the corresponding tooth piece groove through a pin column. The tooth pieces are attracted to the body by means of magnetic force; when a drill protecting pipe penetrates, the tooth pieces turn over by means of pushing force of the pipe, and therefore drill protecting pipe can penetrate smoothly. The drill bit solves the problems that according to a soft coal bed gas extraction drill, penetrating efficiency of the drill protecting pipe is low, and the technology is complex.