Effects of LED (light emitting diode) illuminations of three wavelengths (i.e. 505 nm, 540 nm and 590 nm) on light adaptation and mating of the cotton bollworm Helicoverpa armigera were investigated under laboratory conditions (at (26±1)℃,70%-75％ RH and a photoperiod of L12∶D12).Both continuous and intermittent illumination of all three wavelengths could keep the status of light adaptation of Helicoverpa armigera during night and the rate of light adaptation was from 75% to 100%. LED illumination of 590 nm decreased the mating rate from 89.15% in the control to 52.5% in the treatment, and the number of copulations. LED illuminations of 505 nm and 590 nm changed the oviposition dynamic of H. armigera, prolonged the average oviposition duration about 2 days, and decreased the egg hatching rate significantly, but not affected fecundity.