The ignition system of gas-fired boiler adopts high-energy igniter, which belongs to low-voltage capacitive discharge device. Its main structure is composed of nddh high-energy igniter, nddz igniter and nddl shielded ignition cable. Its working principle is to convert the AC power frequency of 220v into DC pulsating current through boosting rectification and charge the energy storage capacitor. When the capacitor is fully charged, the discharge current is transmitted to the semiconductor nozzle of the ignition gun through the discharge tube, choke coil and shielded cable, forming high energy arc spark. When the ignition device stops working, the remaining charge on the capacitor is discharged through the discharging resistor.