Substation has a critical role in power network because it is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse with power transformers. All devices in substation are controlled, protected and monitored by substation automation system (SAS) that collects information from the power equipment (process) and performs actions on it. Communication network is a fundamental element in all automation system and network performances can have a critical impact on the control process. In the past decade, new communication standard have been designed and retrofitted into substations. IEC61850 is a new international standard for substation automation. In this paper, the authors describe some important feature of IEC 61850 as an international communication standard in substation automation system, that separate this standard from other communication standard in substation.