The resistance background of 6 strains of Botrytis cinerea isolated from cucumber to 6 different kinds of fungicides were examined by mycelium growth rate method，suggesting that their resistant levels to Boscalid were different. The control efficiency of 50% Boscalid WDG on cucumber gray mould was evaluated through potted experiments combined with field trials. In the potted experiments，the control efficiency of 50% Boscalid WDG on 2 strains of Botrytis cinerea with low resistant level were 53.49% and 53.04%，respectively.And the control efficiency of 50% Boscalid WDG on 3 strains of Botrytis cinerea with high resistant level were 50.16%，51.67%，32.24%，respectively. The results showed that Boscalid activity was heavily influenced by the continuously rising of Botrytis cinerea resistance. In the field trials of 2013 and 2014，the control efficiency of 50% Boscalid WDG，at the dosage of 5 625 g·hm^-2，were 94.34%，90.39% respectively. Both 50% Boscalid WDG and 50% Procymidone WP could inhibit Botrytis cinerea effectively at the dosage of 4 500 g·hm^-2. In summary，Boscalid could control the gray mould on cucumber effectively.