The arrival of the big data era facilitates the reform on related research and its application in the fi eld of urban planning from the mode of thinking to the technical method, which provides a technical foundation and platform for supporting the demands of residents as micro subjects in the process of city development. Beginning with analyzing the changes in urban planning thoughts under the infl uence of big data, this paper then summarizes the major reforms in urban planning research methodology and a city’s plan formulation process caused by the application of big data, such as thinking mode, researching method, and planning process, based on which relevant issues like publicity and sharing of data, authenticity of data, and security of data that need to be further discussed and solved are analyzed, with the expectation of promoting the development of urban planning research and application in this new era. The arrival of the big data era facilitates the reform on related research and its application in the fi eld of urban planning from the mode of thinking to the technical method, which provides a technical foundation and platform for supporting the demands of residents as micro subjects in the process of city development. Beginning with analyzing the changes in urban planning thoughts under the inflence of big data, this paper then summarizes the major reforms in urban planning research methodology and a city’s plan formulation process caused by the application of big data, such as thinking mode, researching method, and planning process, based on which relevant issues like publicity and sharing of data, authenticity of data, and security of data that need to be further discussed and solved are, with the expectation of promoting the development of urban planning research and application in this new era.