Abstract: Taking Platanus orientalis street trees in Nanjing as an example, the safety risk evaluation index system of street trees covering 8 evaluation indexes was established by analyzing the growth status, stability, health status, and influence on traffic of street trees, and the safety risk evaluation of all street trees was carried out based on factor analysis and k−means clustering. In Nanjing, 51.7% of the street trees with high or medium risk were located in Qinhuai, Xuanwu, and Gulou districts. Mochou Road and Three Lanes were high risk sections, and the number of high-risk street trees in middle risk sections accounted for 79.1% of the total number of high-risk street trees. Therefore, in addition to close monitoring of high-risk sections, it is also necessary to strengthen monitoring of medium-risk sections. The street tree safety risk evaluation method proposed in this study can obtain scientific and accurate street tree safety risk evaluation results by establishing a reasonable and effective street tree safety risk evaluation model, reflecting the street tree safety risk status, providing decision support for management departments, and is transferable and can be extended and applied to other street tree safety risk evaluation studies.