Abstract: The protective effect of novel elicitor candidate,1,2,3-benzothiadiazole-7-carboxylic acid,2,2,2-trifluoroethyl ester (TBTC) was studied by surface spraying on the cucumber (Cucumis sativus L.) leaves to induce the resistance against the biotrophic downy mildew Pseudoperonospora cubensis in pot and field experiments.The results of pot experiment showed that the control afficacy of TBTC was 77.50%±1.79% at concentration of 250 mg (a.i.)/L,the control afficacy of positive control BTH was 71.72%±2.58% at the same condition,while that of dimethomorph 500 WP was only 71.46%±3.01% at concentration of 500 mg (a.i.)/L.Based on the results of two-year field investigations,the control afficacy varied at an acceptable range for TBTC,BTH and dimethomorph 500 WP.The highest control afficacy of TBTC at 250 mg (a.i.)/L,BTH at 250 mg (a.i.)/L and dimethomorph 500 WP at 500 mg a.i./L were 83.94%±2.09%,72.39%±2.91% and 89.08%±1.95%,respectively.The results suggested that TBTC could induce resistance of cucumber against P.cubensis.