The invention discloses an adjustable clamp for a bolt drilling machine, which comprises a base, a leg is arranged at the bottom of the base, an adjustment rod is threadedly connected to the bottom of the leg, a base is installed at the bottom of the adjustment rod, and the base The top is threaded with a connecting rod, the top of the connecting rod is threaded with a first support plate, the top of the first support plate is slidably connected with a guide block, the top of the guide block is provided with a second support plate, and the second support The top of the plate is slidably connected with splints, the top of both sides of the second support plate is provided with fixed blocks, the fixed blocks are penetrated with a screw rod, one end of the screw rod is provided with a rotating handle, and the other end of the screw rod is provided with a pressing plate , the pressing plate is set close to the splint, one side of the guide block is located on the first support plate and a limit block is provided, and an adjusting bolt is penetrated on the limit block. The present invention can be adjusted up and down, front and rear, and left and right to improve It improves the processing efficiency and has high practicability.