Abstract: Due to its complex structure and diverse functions, DC microgrid has higher requirements on the performance of converters in the system. The four-switch Buck-Boost converter has many advantages, such as wide range of voltage conversion, input and output polarity, power bidirectional transmission and so on. Thus, it has been widely concerned in recent years, and has been used in new energy power generation and energy storage unit of DC microgrid. The working principle and typical control strategy of the converter are analyzed and described, the key problems, including the mode switching and the efficiency optimization, are summarized. Specifically, focusing on the problem of mode switching, the dead-zone mechanism is studied, and some typical optimization methods for smooth-mode switching are analyzed based on the multimode control strategy. Then, for the problem of efficiency optimization, the key factors affecting the efficiency of the converter are summarized, and the common efficiency optimization methods are summarized from hard switch and soft switch control. Finally, the main research contents of converters are compared and summarized, which can provide references for the further research and development of this field.