Abstract: The extreme values of dissolved oxygen (DO) in thermocline include metalimnetic dissolved oxygen maximum and metalimnetic dissolved oxygen minimum (MOM) in stratified lakes and reservoirs. On the basis of systematic investigation of domestic and foreign literatures, the formation causes, formation process, research methods and its impact on the environment of metalimnetic DO maximum and minimum are reviewed; Their similarities and differences from the aspects of formation factors, research methods, lake morphology, biological process and physical process are compared and analyzed. Six causes of MOM are summarized : plankton respiration consumption, organic matter decomposition oxygen consumption, side-slope sediment oxygen consumption, DO vertical transport, water intake from thermocline and its lower position, artificial oxygenation in epilimnetic and hypolimnetic. In conclusion, the application of three dimensional hydrodynamic-biochemical coupling mathematical model should be strengthened in the research methods. In terms of research content, the DO dynamics process of stratified lakes and reservoirs should be further studied from multi-dimensional (vertical and horizontal), and explore the impacts of climate change and extreme weather on DO structure.