Based on the introduction of smart substation function architecture, the analysis method of use case was firstly recommended to study the main business information system of smart substation, involving protective relaying and automatic control. During analysis, demand of information interaction in lengthwise and crosswise direction and limits of the existing system was pointed out. Then in guide of system theory, control theory and information theory, integrated-control idea was proposed to improve the existing control system framework, the integration-control model and system architecture were analyzed. Finally, the project application of yan’an was given.