An ignition circuit includes a system power supply, an ignition coil, a delay unit, a first switch unit, and a second switch unit. When the system power supply is powered on, the second switch unit is turned on, the ignition coil is powered on. After a delay time, the delay unit controls the first switch unit to be turned on, the second switch unit is turned off, the ignition coil is powered off. Therefore an ignition operation is accomplished.