The effects of ultraviolet (UV) light stress on esterase, peroxidases (POX),and catalase (CAT) isozymes in Helicoverpa armigera （Hüber） adults were studied by isozyme electrophoresis. When exposed to UV light irradiation, zymogram of esterase isozyme changed mainly in number and activity of isozyme. After 30 min and 60 min exposure, the intensity of isozyme bands E4,E9 and E10 were enhanced,E2 and E8 were weakened. The bands E1,E5,E7 and E11 disappeared after UV light irradiation, while E3 and E6 newly emerged. At the longest exposure time (90 min), the intensity of isozyme bands E4 and E9 was enhanced, while the intensity of E2 and E8 was weakened. The bands E1,E5 and E7 disappeared after UV light irradiation,whereas E3 and E6 newly emerged. The intensity of POX band P5 was enhanced in adults following the exposure to UV light for 30,60,90 minutes. The intensity of CAT band C1 was enhanced in adults following the exposure to UV light for 30,60，90 minutes, but that of band C2 was weakened after 30 min and 90 min exposure in comparison with the control.