Under the “Internet ＋” environment, the integration of government big data with public services and social sensor data has transformed the urban management model from single to comprehensive, the urban service system from isolation to sharing, and the urban decision-making model from mechanical to intelligent, which is the development trend of government service. In order to solve the problems of insufficient integration of government affairs data, public service data and social sensing data, insufficient sharing, low utilization efficiency and lack of technical platforms, the overall framework of the “Internet ＋” government affairs big data intelligent service platform is proposed. This paper designs the platform construction theory, system architecture, technical architecture, core technology and service application, etc., and realizes the transparent access of the “Internet ＋” government big data intelligent service platform, city information unit, transparent intelligent agent, transparent management and microservices, etc. Exploratory applications have been carried out on platforms such as Digital Guangdong and Dandong Social Security in Liaoning, showing that the platform can effectively support the efficient sharing, management and utilization of government affairs data, public service data and social sensor data, and improve department service effectiveness and capability. The overall design scheme of the platform proposed can provide valuable reference for provincial and municipal governments to carry out the construction of “Internet ＋” government big data intelligent service.