Intelligent state monitoring of substation equipment is an essential factor to realize digitalization of substation information, networking of communication platform and standardization of information sharing. It can also support real-time automatic control, online analysis and decision, cooperative interaction and other advanced features, thus to realize interaction with neighboring substation and dispatching center when necessary. Intelligent state monitoring of electrical equipment can not only ensure proper operation of electrical equipment, but also realize electrical equipment integrated diagnostics using its run state database based on its expert system, so it is the basis of the smart substation. Focused on the present technology of equipment monitoring in substation and combined with the status in this area and the development direction of smart grid in recent years, this paper gave summary of intelligent condition monitoring system for substations.