The invention discloses a pre-combustion chamber ignition structure, a pre-combustion chamber ignition system and a working method thereof. The pre-combustion chamber ignition structure comprises a central electrode extending into a pre-combustion chamber; a grounding electrode is disposed to an end portion of the central electrode; and a spark plug clearance located inside the pre-combustion chamber is formed between the central electrode and the grounding electrode. According to the pre-combustion chamber ignition structure, pre-combustion chamber ignition system and working method thereof of the invention, more mixed gases participate in combustion in the pre-combustion chamber; jet flow components entering a main combustion chamber through the connection passage of the pre-combustion chamber after the spark plug performs ignition can be significantly improved; energy carried by the jet flow of the pre-combustion chamber can be increased; a distributed ignition coverage area formedafter the jet flow of the pre-combustion chamber enters the main combustion chamber can be increased; the ignition energy of the ignition system of the pre-combustion chamber can be significantly improved; and the reliable ignition of a lean mixture in the main combustion chamber can be ensured; the propagation distance of flames in the main combustion chamber can be shortened; the lasting duration of combustion in the main combustion chamber can be shortened; combustion heat efficiency can be improved; the cyclical fluctuation ratio of the operation of an engine can be reduced; the operational stability of the engine can be significantly improved; and HC and CO emissions can be reduced.