The invention discloses a cutting device which comprises a cutting gun body and a cutting nozzle, wherein, the cutting nozzle comprises a cutting nozzle core and a cutting nozzle sleeve; the cutting nozzle core comprises a nozzle core body, a cutting oxygen channel, a first boss, a first preheating hole, a second preheating hole and a preheating tank, and the cutting nozzle sleeve comprises a nozzle core assembling hole; the cutting nozzle core is assembled in the cutting nozzle sleeve, and the cutting nozzle core and the cutting nozzle sleeve are integrally assembled in the cutting gun body; and the cutting gun body comprises a gas pipe, a preheating oxygen pipe and a cutting oxygen pipe, and the cutting oxygen pipe is communicated with the cutting oxygen channel of the cutting nozzle core. The cutting device has the following technical effects of concentrated flame, fast cutting speed, bright and clean section, narrow slots, less steel and energy consumption, no black smoke during the cutting process, environmental protection and small noise.