The invention discloses a device and a method for temporarily sealing leakage of a gas pipeline ripple compensator. The device comprises a bowed brick, wherein the bowed brick is made of a steel plate and the radian of the inner wall of the bowed brick conforms to the outer-diameter ripple radian of the ripple compensator; a steel plate bracket is arranged at the upper part of the bowed brick; one end of the steel plate bracket is connected with the side all of a pull rod on one side of the ripple compensator, and the flat surface of the steel plate bracket is vertical to the side wall of the pull rod; the steel plate bracket is provided with a plurality of nuts with long full-wire screw rods, and a space between the inner wall of the bowed brick and the outer diameter of the ripple compensator is filled with asbestos cloth; the method comprises the steps of size measurement, bowed brick manufacturing, steel plate bracket welding, welding of nuts on the steel plate bracket, installation of the long full-wire screw rods, asbestos cloth filling, leak source sealing, real-time monitoring and the like. The device has the advantages of being simple in structure, convenient in operation, rapid in sealing, good in practicability, capable of sealing the leak source of the ripple compensator in time, and free from off production in a sealing process, thereby avoiding the potential safety hazard of coal gas leakage and reducing the equipment accident possibility and the maintenance time.