This paper conducted experiment on controlling bitter gourd powdery mildew using Bacillus
subtilis（BLG010）．And in order to find out the pathogenic process-related substances，the paper analyzed
the differences in metabolic substances of bitter gourd leaves 8 days and 15 days after pathogen inoculation
treatment，pathogen+BLG010 inoculation treatment and distilled water spraying treatment by GC-MS
methodology．The results showed that the control effect of BLG010 on bitter gourd powdery mildew was as
high as 89.49%．After pathogen infection，the contents of D-glucose，fumaric acid and galactinol on 8 days
and 15 days were all up-regulated．While，the contents of glycine，glyceric acid，L-glutamic acid and caffeic
acid were down-regulated．Contents of these 7 metabolic substances were related to the pathogenic process of
bitter gourd powdery mildew．Application of BLG010 can decrease the disease index，and avoid the abnormal
changes in contents of these 7 metabolic substances．