Abstract: A carbendazim-susceptible isolate and a carbendazim-resistant isolate of Botrytis cinerea were compared with regard to mycelial growth and the extreme value of conductance upon treatment with the benzimidazole fungicide carbendazim hydrochloride. The result showed that the EC50 value of carbendazim-susceptible isolate was 0.062 0 mg/L, while the carbendazim-resistant isolate formed normal colony on PDA containing 1 000 mg/L carbendazim hydrochloride. Under the treatment of carbendazim hydrochloride with the concontration of 5 or 10 mg/L,the conductivity of carbendazim-sensitive isolate showed a decreasing tread,but that of carbendazim-resistant isolate only changed a little.