This paper describes concept and importance of time performance of communication network and system in substation and provides measurable and analysable method for management and maintenance of communication network and system in substation. According to conformance testing of communication network and system in substation, it defines test method and test range for time performance, and discusses the importance of test method. Through the analysis of test method, it defines the basic of requirement of time performance and meanwhile describes evaluation parameters for substation, which provide a comprehensive method and measure reference for the management of substation time performance.