The utility model provides a spray gun locking device, spray gun locking device includes: removable assecmbly's spray gun and fastener, wherein the fastener cover is established on the spray gun, theouter wall of spray gun is provided with seal structure, the fastener include with the fastening structure that seal structure corresponds, it is right to be used for seal structure fastens and is right the spray gun with the fastener seals. According to the utility model discloses a spray gun locking device, removable assecmbly's spray gun and fastener have reduced the processing degree of difficulty and processing cost, can reduce the cost in long -time operating maintenance and in changing, and dismantle easily, and the operating mode of assurance boiler is stable, pass through simultaneously the fastening structure of fastener is right the seal structure of spray gun fastens, has both guaranteed between spray gun and the fastener the fixed of relative position, leakproofness in the time of guaranteeing to move again.