The increasing concentrations of CO2 and O9 in troposphere have become a focus of attention from both domestic and foreign researchers. The effects of single and joint action of CO2 and O3 on secondary metabolism of crops and decomposition of organic residues were summarized, and further researches on this area were prospected in this paper. This paper aims at introducing the effects of the compounds on secondary metabolism of crops attended by introducing composing approach and function of secondary metabolism and impacts of elevated CO2 and O3 concentrations. It brought the attention on the effects of elevated CO2 and O3 concentration on crop productivity, secondary metabolism and residue decomposition, especially for the interactive effects of elevated CO2 and O3, and impersonality expressed the biological and ecological effects.