The first full-scale u-City operation has started in Dongtan u-City. As local cities take over and operate the u-City, unexpected issues arise such as securing the budget of operating costs and self-providing the costs with business models utilizing the u-City assets. The paper presents a strategy for solving these issues. The strategy provides a foundation(infrastructure) for long-term operation models which may reduce the long-term operating costs. In order to establish the economic operating framework of u-City, suggested are some cost-reduction models based on the operating costs structure. For each model, a base framework with comparative analysis of operating costs is provided. With these models, each u-City may select a relevant model according to the characteristics of it. We hope that the framework provides the foundation for efficient and sustainable u-City operations.