Abstract: This paper deeply discusses the outdoor installation mode of smart substation fault recording device in the overall plan and route, by actively promoting the technology innovation of fault record to " device miniaturization, outdoor installation and standardization " as the general principles. Through the secondary equipment in outdoor unprotected installation and functional integration to achieve device miniaturization and local installation; by aerial plug interface standardization to achieve replacement maintenance; and a secondary device topology rule definition and model description is given to achieve the fault recording data expert remote diagnosis. As the plan is intended to consider fault recording device overall demand as a whole in the substation secondary equipment, it is applicable to the relevant technical standard system construction, and of positive significance for speeding up completion of equipment development of 220 kV and above under all kinds of bad working conditions of substation construction commissioning.