The invention discloses a paint spraying device for a construction site. The paint spraying device comprises a shell, a spraying mechanism, an air injection mechanism and a transmission mechanism, wherein two handles used for holding are arranged at the bottom of the shell, the spraying mechanism is mounted in the shell, so that paint and compressed air are mixed and sprayed out, the air injection mechanism is mounted on the outer side of the spraying mechanism, so that floating ash on the wall surface is blown away by the spraying mechanism before paint spraying, the transmission mechanism is installed in the shell, and when the transmission mechanism moves, the spraying mechanism and the air injection mechanism work synchronously, floating ash on the wall surface is blown away, and paint spraying is conducted. According to the paint spraying device, the spraying mechanism is combined with the air injection mechanism to spray paint on the wall surface, dust needs to be removed on the part, needing to be sprayed, of the wall surface while spraying is conducted, therefore dust on the spraying portion is reduced, even if the wall surface is not completely cleaned, the air injection mechanism can also clean the wall surface in advance, so that the spraying effect of the wall surface is ensured, the time for repairing paint on the wall surface is shortened, and the labor cost is reduced.