Considering the recent developing trends of power grid enterprise towards digitalization and informatization， the enterprise application integration（EAI） is adopted to solve the“information island” problem. The evolution process of traditional EAI solutions is reviewed. It is pointed out that the integration technology based on service-oriented architecture（SOA） is an important pattern to achieve EAI of power grid enterprise. The SOA-based EAI architecture is proposed and the implementation schemes are designed respectively for data integration layer and business process integration layer so that the integration platform can provide CIM-based standard data and achieve the automatic execution of typical business process. Finally， the SOA-based EAI of Shanghai Municipal Electric Power Company（SMEPC） is introduced.