As urbanization accelerates and awareness of environmental conservation rises, the optimization and modernization of public transportation systems, crucial to urban infrastructure, encounter novel challenges and prospects. While public transportation has evolved in the past few years, the city still grapples with issues of inefficiency and poor passenger contentment, hindering its sustainable growth. In this context, there's an immediate need to investigate the ways in which creative optimization strategies can enhance the efficiency of public transit systems and aid in building cities that are both environmentally sustainable and conserve resources. Based on the above, this paper focus on the optimization strategy of the public transportation system and its impact on sustainable urban development. Firstly, the analysis focuses on the current status and challenges of public transportation systems, examining how these relate internally to objectives of sustainable development. Secondly, the leading strategies and technical frameworks for optimizing public transportation systems are presented from theoretical and technical aspects, especially the application value of big data analysis, intelligent scheduling systems, and energy-saving and emission-reduction technology. In addition, the researchers constructed a model to analyze the positive effects of optimization strategies on urban traffic flow, system efficiency, and environmental quality. They verified the actual effectiveness of these strategies through case analysis. To sum up, the research highlights the vital importance of effective and eco-friendly public transportation in lessening city traffic jams, enhancing the living standards of inhabitants, and curtailing carbon emissions. Furthermore, it offers practical experience and strategic advice for other cities.