Abstract: An ignition device for an underground coal gasification process, and an underground coal gasification method for carrying out ignition. The ignition device comprises a conveying device, a cut-off device (7), an ignition detonator (6) and one or more fuel packs (5), sequentially connected. The fuel packs are serially connected with each other. The conveying device is a coiled tubing/conjugation tube (12), or an integrated signal cable (21). The ignition detonator runs through one or more fuel packs and ignites the one or more fuel packs starting from the top of the device in a delayed manner. The cut-off device breaks off after the ignition detonator is started, so that ignition device components comprising the conveying device are at least withdrawn to a safe position. Each fuel pack comprises thermite and is used for igniting an underground coal seam (1) after the fuel pack is ignited.