The invention provides an arm unfolding gripper mechanism of an industrial robot. The arm unfolding gripper mechanism comprises a gripper frame, a driving device, a pushing fixing piece, a movable rotating arm, a fixed rotating arm, a fixed shaft and push rods on the two sides of the gripper driving device, wherein the push rods drive the pushing fixing piece to horizontally move towards the two sides, the pushing fixing piece pushes the movable rotating arm and the fixed rotating arm to move, so that the movable rotating arm and the fixed rotating arm do composite motion; the inclination angle of the fixed rotating arm is changed while the fixed rotating arm moves outwards, the fixed rotating arm is gradually inclined from the vertical direction to the outside, and the fixed rotating armdrives a gripper to move, so that the gripper is opened towards the two sides; and when the driving device tightens the pushing fixing piece, the angle of the fixed rotating arm is gradually changed to the vertical direction, the fixed rotating arm drives the gripper to move, so that the gripper is tightened towards the inner side. According to the arm unfolding gripper mechanism, large-stroke movement of the gripper is realized through a small-stroke movement mechanism, and the capacity of the gripper is improved. The arm unfolding gripper mechanism is ingenious in structure, elegant in appearance, capable of rapidly and effectively driving the gripper to move, capable of guaranteeing that automatic feeding and discharging equipment is smooth and stable during working, high in applicability and beneficial to assembly, disassembly and maintenance.