Abstract: The in vitro bioactivities of four fungicides (carbendazim, iprodione, pyrimethanil, propiconazole) against Botrytis cinerea from tobacco were investigated using mycelial growth rate method and spore germination method. Their protective and curative activities against grey mould on detached leaves were investigated. The results showed that the four fungicides had different inhibitory activities. The fungicide with the highest toxic potential against the mycelial growth of B. cinerea was carbendazim with average EC₅₀ value of 0.06 mg/L, followed by propiconazole, pyrimethanil and iprodione, with average EC₅₀ values of 0.36, 0.53 and 0.60 mg/L, respectively. The EC₅₀ values of fungicides against spore germination were as followings: iprodione (2.05 mg/L), propiconazole (2.21 mg/L), pyrimethanil (10.56 mg/L) and carbendazim (131.23 mg/L). The most effective fungicide with the best protective and curative activities was iprodione and carbendazim. At the concentration of 200 mg/L, protective control efficacies were both 100% and the curative efficacies were 98.3% and 91.8%, respectively. This study provided scientific basis for guiding the control of tobacco grey mould.