The invention discloses a surface paint spraying device for timber processing. The device comprises a processing carriage, a paint barrel and a fixing mechanism; a base is arranged at the bottom of the processing carriage; the paint barrel is fixed above the base; a driving motor is mounted in an inner cavity of the base; a transmission shaft is mounted at the top end of the driving motor; the transmission shaft extends into the paint barrel, and is provided with multiple stirring rods; a transmission gear is mounted on the transmission shaft, and is positioned below the paint barrel; a transmission rack is mounted on an upper plane of the base; fixed blocks are connected to the front and back ends of a bottom plane of the transmission rack; first pulleys are mounted at the bottom ends ofthe fixed blocks; a first chute is formed in the upper plane of the base; the first pulleys are mounted in the first chute; and the transmission rack is in tooth pattern engagement with the transmission gear. The device performs automatic sealing operation, prevents volatile gas in the coating process from dispersing in air, and prevents harm to operators.