Early studies on plant secondary metabolites (natural products) were generally resulted from their application values. In recent years the bioactivities of secondary metabolites have been more and more realized and their potential roles in plant living activities and ecosystem have been reevaluated. Plant secondary metabolism is a consequence of the interaction between plants and environments (biotic and abiotic) in the long process of plant evolution. Plant secondary metabolites play important roles for plants to improve defensive and competitive abilities as well as correspond to the environments. In this overview, we briefly introduced the characteristics of plant secondary metabolism, summarized the relationship between secondary metabolism and abiotic factors such as temperature, water, light, nutrient, CO2 concentrations, UV-B radiation and environmental pollutions, and the relationship between secondary metabolism and chemical defence, allelopathy, mycorrhizal symbiosis and micropathogens. Research on the interaction between plant secondary metabolism and environments may explore more profound understandings and new approaches to comprehensive correlations between plants and environments. It also may benefit the efficient and rational utilization of the secondary metabolites.