The utility model discloses a bottom concealed type cleaning bin for spray gun outside cleaning. The cleaning bin comprises a spray gun cleaning bin body arranged at the bottom of a powder spray booth, wherein a bottom plate assembly is arranged above the spray gun cleaning bin body to isolate a powder spray area of the powder spray booth from a cleaning area, the bottom plate assembly can be opened or closed in a turnover manner, when color change cleaning is required, the bottom plate assembly is rotated to a perpendicular position, a spray gun can be lowered to be located in the spray gun cleaning bin body, then the bottom plate assembly is rotated to a horizontal position, the cleaning area isolated from the powder spray area is formed in the spray gun cleaning bin body, cleaning is performed by a spray gun cleaning mechanism instead of manpower, and inner walls of the powder spray booth can be cleaned synchronously when isolated cleaning is performed on the spray gun in the spray gun cleaning bin body, so that the cleaning efficiency is greatly improved, the time spent on color change is shortened, and the working efficiency of the powder spray booth is improved.