Rising atmospheric CO₂ concentration has been regarded as a key global environmental problem today: it is expected to influence changes in plant eco-physiology. The research advances on the effects of elevated CO₂ concentration on tree eco-physiology were reviewed: this included the effects of elevated CO₂ on growth and development, photosynthesis and respiration, antioxidative systems, volatile organic compounds (VOCs), and litter decomposition of trees. Generally, elevated CO₂ enhances the growth and development of trees and the results vary with tree species. The turnover in fine roots of trees was accelerated by elevated CO₂, which may play an important role in the cycle of global carbon in forest ecosystems. Elevated CO₂ increases net photosynthetic rate for most tree species. However, photosynthetic acclimation in some tree species sometimes occurred under elevated CO₂ concentrations, and it was still uncertain as to whether it revealed the physiological mechanism underpinning the occurrence of photosynthetic acclimation of trees to date. The effect of elevated CO₂ on root respiration of trees will be an important aspect of the study of forest ecosystems under a changing climate. The activities of antioxidative enzymes and the contents of antioxidants in trees were generally maintained at high levels under elevated CO₂ concentrations. The process and mechanism of antioxidative system response to elevated CO₂ concentration were associated with certain tree species. Although the adverse effect of elevated CO₂ on the decomposition of tree litter has been observed in recent studies, it also depends on tree species. Numerous studies were focused on the apparent physiological responses of trees to elevated CO₂. However, little is known about the physiological processes including coupling of carbon, nitrogen, and water, or gene regulation under elevated CO₂ concentrations, particularly in the underground parts of trees. Many studies have been carried out based on individual plant levels, but there has been a lack of comparative studies of the response of different tree species or varieties to elevated CO₂ concentrations. Little information exists about the long-term study of the key processes and mechanisms of physiological metabolism of fine roots under the action of multiple environmental factors. The perspectives in studies of tree eco-physiology under elevated CO₂ concentrations were summarized, including research into the physiological mechanisms of tree root metabolism, coupling in carbon, nitrogen and water processes, responses and adaptations to multiple environmental factors, and related molecular mechanisms under elevated CO₂ concentrations. This research will enrich the knowledge relating to the responses and adaptations of forest trees to climate change, especially for the sustainable management and operation of forest eco-systems and the selection of tree species.