Focusing is a key part of the launch focusing device in high-energy laser systems, and the focusing mechanism plays an important role in the targeting and striking accuracy of the system. In order to understand the research status and development trend of focusing mechanism, various types of foreign mature focusing mechanisms are introduced firstly. The principle of their focusing control and the solutions of various technical problems are analyzed. The domestic research situation focuses on four types of focusing mechanisms: cam, screw, worm gear and direct drive. For each form of focusing mechanism, the basic principle of controlling focusing is analyzed, and the design features of the focusing mechanism applied to different systems are introduced. By analyzing the design and control of each type of focusing mechanism, the advantages and disadvantages are summarized and compared, and the design ideas and research directions of the focusing mechanism for high-energy laser systems are proposed to lay the technical foundation for the research on focusing mechanism of high-energy laser systems.