The development of power system faces many challenges. Smart grid（SG） is regarded as an effective solution. An open and common information system is the basic of SG. This paper analyzes problems of power grid information system today， proposes a framework of SG information system， and emphasizes the importance of digitalization and standardization of basic data. Considering the significant role of substations in power grid， a framework for basic data platform of substations is designed. The platform can provide basic data with standardized protocol， standardized format，synchronous timestamps and all-in-one management，and can be cascaded and expanded into a SG information system with structure unchanged.