The invention discloses a closed tobacco-leaf front-back-face material adding device. The closed tobacco-leaf front-back-face material adding device is characterized by comprising a leaf feeding system, a flow dividing system, a tobacco leaf inlet, an atomizing chamber, an atomizing chamber sealing plate, a liquid injection nozzle and a leaf outlet conveying belt. The closed tobacco-leaf front-back-face material adding device has the advantages that the structure is simple, the material adding evenness is high, the tobacco leaf breaking rate is low, the adding accuracy and the adding stability are good, and continuous large-scale production can be achieved; as materials are added to the front face and the back face of tobacco leaf flow in a closed mode, the tobacco material adding process can be more fine and more evenly controlled, and the tobacco material adding effect can be effectively improved.