The invention discloses a cement flattening compacting device for road construction. The cement flattening compacting device comprises a rack and a base. The rack is mounted on the base, and the rackis provided with a material box, a conveying mechanism, a transmission device and a transmission frame. The transmission device comprises a sliding bar, the sliding bar is vertically mounted on the rack, a top plate and a bottom plate are mounted on the sliding bar, the top plate and the bottom plate are mounted on the sliding bar through sliding sleeves, the top ends of the top plate and the bottom plate are provided with a first transmission link for connecting the two, the front ends of the top plate and the bottom plate are provided with a second transmission link for connecting the two, the transmission frame is mounted at the rear end of the rack, a sliding frame is mounted inside an inner cavity in the transmission frame, sliding blocks are mounted at the upper and lower ends of thesliding frame, the upper and lower sides of the inner wall of the transmission frame are provided with sliding rails, and the sliding blocks are limited in the sliding rails. The cement flattening compacting device has high stability and high operation consistency, can perform fully automated operation, and can save a lot of human resources.