Abstract: With the acceleration of offshore wind power development, offshore wind power is shifting from near sea to deep sea. Within a certain distance range, low-frequency AC transmission systems have a cost advantage. With the gradual transition of low-frequency AC transmission systems from theoretical research to practical application, there are currently multiple demonstration projects in China, such as the 35 kV offshore wind power flexible low-frequency (20 Hz) transmission in Taizhou, Zhejiang. Through analysis and simulation calculations of the opening and closing processes of a 20 Hz low-frequency circuit breaker, the difference between 20 Hz and 50 Hz circuit breakers is found. The opening arc energy of a 20 Hz low-frequency circuit breaker is significantly increased, and special attention should be paid to the contact erosion ability to provide reference for the development of 20 Hz low-frequency circuit breakers.