Abstract: With the popularity of 5G applications in substations, more and more 5G base stations need to be built in substations. The communication equipment in 5G base station is affected by complex electromagnetic environment. The existence of external antenna challenges the electromagnetic protection of 5G base station. This paper analyzes the electromagnetic disturbance factors and calculation methods of the substation to 5G base station, expounds the analysis process with a simplified model of a 500 kV substation as the object, and discusses the main influencing factors, suppression methods and site selection suggestions, so as to provide reference for improving the electromagnetic compatibility between secondary equipment and 5G communication equipment in the substation and the deployment of 5G communication equipment in the substation.