The utility model discloses a tobacco topping spraying mechanism which comprises a guiding cutting mechanism and a spraying executing mechanism, the guiding cutting mechanism comprises two guiding fork plates and a rotary cutting knife set which is arranged above the guiding fork plates and used for topping off the tops of tobacco plants, and a linear guiding channel allowing the tobacco plants to pass through is formed between the two guiding fork plates. The spraying execution mechanism comprises a bud inhibitor spray head for spraying a bud inhibitor to the cut of the tobacco plant. According to the tobacco topping and spraying mechanism, synchronous same-plant topping and bud inhibition agent spraying can be conducted on tobacco plants, tobacco topping and bud inhibition mechanized operation can be achieved, labor intensity is reduced, the field operation frequency is reduced, and tobacco topping work efficiency is improved.