[Objective] The humidity of the greenhouse was reduced by fan internal recycle ventilating during the night to decrease the occurrence of condensation,prevent pathogen infection and reduce the probability of Corynespora cassiicola( Berk. & Curt.) Wei. of cucumber.[Method]By means of random investigation,grading research was carried on Corynespora cassiicola( Berk. & Curt.) Wei. of cucumber with the fan blown and out,and the data was analyzed. [Result]The fan ventilating had effect on controlling the develop...