Abstract: Objectives:  With the rapid urbanization in China, the contradiction between the ever-expanding population size and the limited space resources has brought many challenges to urban and rural planning and construction management, and also affected the people's emotional attitude towards urban space. How to make full use of geographic data and public opinion big data, to organize multidimensional and complex geographic information and online public opinion information in urban planning has become a difficult issue in the research of online public opinion. Based on the idea of geographical case, this paper proposes the concept of urban planning case and organizes geographical information and public opinion information in urban planning in an ord erly way.   Methods:  The urban planning case description model is constructed according to the triplet form of “case problem, case attribute, and case result”. On this basis, case problem, case attribute and case result of urban planning case are quantitatively expressed, and the expression framework of urban planning case is constructed.   Results:  Finally, a specific planning project is taken as an example, to illustrate the description and expression method of urban planning case.   Conclusions:  The proposed method realizes the abstract description and quantitative expression of geographic information and online public opinion information in urban planning, reduces the redundancy of the composition of the urban planning network public opinion, and provides theoretical support for the similarity calculation of urban planning cases.