The O2O is a fast-growing emerging business model, the O2O business model framework is established and the most basic 7 major elements are identified in our research with Value Net theory as follow: customer, telecom operator, content provider, service provider, software provider, third-party payment platform and offline business entity. Then, we apply the Delphi method to identify 8 secondary elements and 22 three-level elements of O2O business model, and the O2O business model core essential elements evaluation model is also established. We analyze the model systematically and find out 10 core elements with Analytic Network Process (ANP) as follow: network speed and stability, mining the customer subject requirements, customer insight, control the trading risk, the core technology research and development, the life service payment platform, after payment platform, financial services platform development, the detonation of the fulfilled requirements and direct correlation between the maintenance of the enterprise. The 10 elements mainly concentrated in 4 dimensions as follow: customer, telecom operators, software providers and third-party payment platform. We hope that our research can provide enlightenment to O2O enterprise's development and the future trend analysis, and be helpful for all participants of Value Net achieve win-win symbiosis.