The utility model discloses a trigger type spark gap comprising a gap trigger system, a self-discharging type main gap G1, a self-discharging type main gap G2, a partial pressure capacitor Cf, and a voltage-sharing capacitor. A main gap branch can be formed by serially connecting the self-discharging type main gap G1 and the self-discharging type main gap G2, and is respectively connected with a lower voltage end and a high voltage end of the power grid. The partial pressure capacitor Cf is serially connected with the voltage-sharing capacitor, and then is parallely connected with the main gap branch. The gap trigger system is parallely connected with the self-discharging main gap connected with the lower voltage end of the main gap branch. The trigger type spark gap is advantageous in that the strongly practical design method is verified in the engineering, and the spark gap adopting the principle has a higher trigger discharging reliability, which is proved by the practice.