Abstract: Driven by the goal of "carbon peak and carbon neutrality" in China, the power system of China is developing in the direction of low carbon, clean, efficient and intelligent operation. When large-scale renewable energy is connected to the power system, the existing power network has the problem of insufficient transmission capacity. The frequency division transmission system uses lower frequency to transmit electric energy. Compared with the power frequency system of the same voltage level, the line transmission capacity has been greatly improved. At present, it has been widely concerned in the field of efficient collection and transmission of renewable energy, including medium and long-distance offshore wind power, onshore wind power, photovoltaic power generation and large-scale hydropower transmission in remote areas. This paper first introduces the basic principle of frequency division transmission and summarizes the operating characteristics of the core frequency conversion equipment. Under the "double high" background of high proportion of renewable energy access and high proportion of power electronic equipment applications, the operating characteristics and typical design methods of control strategies of point-to-point two-terminal and multi-terminal interconnected frequency-division transmission systems are further elaborated from the aspects of system steady-state operation and fault ride-through. Finally, the prospects in issues are put forward that need to be further combined in the research of frequency division transmission system operation control, such as economic optimization of transmission frequency, stability analysis of small and large interference system, and expansion and transformation of urban power grid.