Abstract: To study the effect of elevated CO₂ on development and reproduction of three consecutive generations of green pea aphid (Acyrthosiphon pisum), the reproductive performance of three consecutive generations of green pea aphid fed detached Vicia faba leaves was recorded under ambient CO₂ [(375±18) μL/L] and two elevated CO₂ concentrations: moderate [(550±27) μL/L] and double ambient [(750±37) μL/L]. It was found that developmental duration of three consecutive generations of green pea aphid was shortened, while larval weight, adult weight, weight difference and mean daily relative growth rate all displayed increasing trends under elevated CO₂ conditions. Also, the reproductive period was prolonged, and the average and maximum fecundity of larvae were both increased. Net reproductive rate (R₀) of three consecutive generations of green pea aphid was increased and generation time (T) prolonged, while intrinsic rate of increase (r_m) and finite rate of increase (λ) were decreased. The population of green pea aphid declined under elevated CO₂ conditions. Hence, elevated CO₂ may have negative effects on green pea aphid population numbers.