In the context of rapid urban development, urban management faces realistic problems such as data silos, system isolation, and inefficient resource allocation. It is urgent to achieve cross-departmental and cross-system collaboration and optimization through informatization. To solve the above problems, this paper proposes an urban information system integration framework for multi-source heterogeneous data fusion, focusing on the integration and application of informatization technology in smart city construction. First, the data standardization technology based on semantic model is adopted to achieve data semantic alignment and format unification among various urban subsystems. Then, the microservice architecture and the concept of middle platform are introduced to build an integrated platform with high scalability and decoupling capabilities. Subsequently, the hybrid deployment strategy of edge computing and cloud computing is combined to achieve local distribution and global optimization of data processing tasks. Finally, a unified urban knowledge graph is constructed to improve the level of data-driven intelligent decision-making. In the response speed evaluation of 100 requests, the average response time of the microservice architecture is 0.0767 s, which is significantly lower than the 0.5913 s of the monolithic architecture. In addition, the microservice architecture can effectively reduce the task execution time and improve the overall performance of the system. In the above data conclusions, the practical application potential of the framework proposed in this paper in smart city management has been verified, and it provides strong technical support for the future construction of smart cities.