The invention discloses a two-sided paint spraying device used for building timber spray finishing. The two-sided paint spraying device used for building timber spray finishing comprises a base, the two sides of the upper end of the base are connected with supporting frames, the upper ends of the supporting frames are connected with top plates, and the middles of the top plates are connected with a drive box. The two sides of the lower end of the base are connected with supporting legs, the right end of the left supporting leg is connected with a drive motor, the right end of the drive motor is connected with a drive shaft, and the right end of the drive shaft is connected with a driving gear. The upper end of the driving gear is meshed with a driven gear, the middle of the driven gear is connected with a transmission shaft, the two ends of the transmission shaft are connected with transmission belt wheels, the upper end of each transmission belt wheel is connected with a turnover belt wheel through a belt, and the middle of each transmission belt wheel is connected with a turnover shaft. The inner end of each turnover shaft is connected with a telescopic cylinder, the inner side of each telescopic cylinder is connected with a telescopic shaft, each telescopic shaft is connected with a U-shaped plate, and the upper end and the lower end of each U-shaped plate are separately connected with a clamping device. The two-sided paint spraying device used for building timber spray finishing realizes two-sided spray finishing of building timber; a horizontal paint spraying mode is adopted, and compared with a vertical paint spraying mode, evenness of timber paint spraying is increased.