Abstract: Since the industrial revolution, the huge consumption of fossil fuels and unduly destruction of natural habitats by human activities have led to the everincreasing concentration of atmospheric CO₂. To study the adaptation mechanisms of plant, herbivorous insect, and its natural enemy within agricultural ecosystems to the elevated atmospheric CO₂ concentration is of significance in deciphering the damage pattern of agricultural pest occurrence and controlling the pest occurrence  and in mitigating the CO₂ emission from agricultural ecosystems. This paper reviewed the research progress on the effects of elevated atmospheric CO₂ on the host plant, herbivorous insect, and its natural enemy in agroecosystem, with the focuses on the improvement of related research methods, the variation patterns of host plant primary and secondary metabolites induced by elevated atmospheric CO₂, the effects of the elevated CO₂ on the growth and development, population density, and behaviors of herbivorous insect, and the biology and predation and/or parasitism rates of natural enemy. The future research frontiers in this research area were also discussed.