The effect of ethanol extract of Eupatorium adenophorum Spreng on growth, development and reproduction of the cotton bollworm, Helicoverpa armigera (Hübner), was bioassayed in the laboratory. The results showed that the mortality rate of H. armigera larvae was significantly higher while pupa weight and adult emergence were significantly lower than the control when the larvae fed on the diet containing the extract of E. adenophorum at the concentrations of 0.088，0.44，2.2 and 11 g/kg. Treatments with the extract at the concentrations of 0.08, 0.4 and 2 g/L showed attraction effect on the oviposition of the bollworm females, however, the extract treatment at the concentration of 10 g/L showed the repellent effect on the oviposition of the bollworm females. Egg hatching success of cotton bollworm in all treatments of the extract decreased significantly compared with the control. The results suggest that feeding the extract of E. adenophorum may obviously retard growth and reproduction of the cotton bollworm.