Abstract: This article takes practical engineering cases as an example to illustrate the selection of different types of circuit breakers for 10 kV and below power systems, and explains the selection of parameter models for various circuit breakers under different voltage levels. The focus is on selecting appropriate circuit breaker models based on the design manual and national standard requirements, after calculating important parameters of the power system, in order to meet the requirements of national standard specifications and achieve economic rationality in equipment selection.