The invention relates to an ignition circuit of a separately-excited arc lighter. The ignition circuit comprises a direct-current power supply, a square wave generating circuit, a first driving and voltage boosting circuit and a first discharging needle, wherein the first driving and voltage boosting circuit comprises a power switch tube and a high-voltage transformer, a winding of the high-voltage transformer consists of a low-voltage winding and a high-voltage winding, and the power switch tube and the low-voltage winding in the high-voltage transformer are connected in series and then are connected to the two ends of the direct-current power supply; the first discharging needle is connected with the output end of the high-voltage winding, and a first driving branch is connected between the output end of the square wave generating circuit and the control end of the power switch tube; the power switch tube is disconnected and connected under the control of the output of the square wave generating circuit through the first driving branch, so that the current on the low-voltage winding is controlled. Due to the adoption of the separately excited driving mode, the ignition circuit is stable in work frequency, low in noise, large in instant starting power, easy to realize arc striking and reliable in work. Besides, the winding of the high-voltage transformer only consists of the low-voltage winding and the high-voltage winding, so that the production cost and the defective rate of the high-voltage transformer are reduced, and massive production is facilitated.