Abstract: An improved structure of an ignition sparking plug having a grounding electrode and a central electrode is disclosed. The grounding electrode has a tip end with respect to the central electrode so that the only a small part of the central electrode is shielded by the grounding electrode. Thereby, mixed gas enters into the space between the grounding electrode and the central electrode rapidly so as to be ignited and then explode quickly to push the piston. Therefore, the piston can move reciprocally. Since the grounding electrode has a smaller volume, the generated spark has a large volume and absorbs a little thermal energy. Since electric discharging occurs in a tip point, the efficiency of ignition is high so as to improve the air to oil ratio in the cylinder and thus oil is saved and exhausted waste is reduced.