Abstract: Under natural conditions, light plants receive usually changes. Thus, the plants have formed corresponding adaptation mechanism in the evolutionary process, which could maintain the energy balance between two light reactions in the process of light changing. Through the movement of leaves and chloroplasts, as well as the accumulation of light-absorbing pigments, plants could regulate light absorption. Also, plants have a mechanism for greatly regulating the distribution of energy absorbed by light-harvesting complex. Especially at low light intensities, plants could mediate reversible phosphorylation of light-harvesting complexⅡ (LHCⅡ) by regulating kinase and phosphatase in relation to the redox state of the electron transfer chain, which could thereby regulate the allocation of excitation energy between photosystem I (PSI) and photosystem Ⅱ(PSⅡ). The state transitions are the quite significant mechanism of plants for adapting to the change of light environment. In this paper, the research progresses of state transitions during the change of light environment were summarized, especially the significance and functions of reversible phosphorylation and movement of LHCⅡ between PS I and PSⅡ were discussed. Finally, the future research direction on state transitions of plants was briefly proposed.