Based on the idea of sustainable development, this paper explores the planning and development of smart cities. Cities face many issues as global urbanization picks up speed, including environmental pollution, resource depletion, traffic congestion, and social inequality. To address these challenges, the notion of sustainable development has become a guiding principle for many city policymakers, aiming to meet contemporary needs while safeguarding future development. Smart cities utilize advanced information and communication technology to enhance urban operational efficiency, improve resource management, and enhance residents' quality of life, thereby providing a more sustainable development model for cities. This paper focuses on the key areas of smart city planning, including energy utilization and environmental protection, smart transportation and urban mobility, smart city planning and land use, social equity, and community engagement. Using Shenzhen as a case study, the practical application of the notion of sustainable development in smart city construction is elucidated, providing valuable insights and practical references for future smart cities.