<p>The analysis of the spatio-temporal evolution of traffic accident hotspots has important guiding significance for understanding the spatio-temporal distribution of urban traffic accidents, gaining insights into the mechanisms of traffic accidents, and formulating traffic accident prediction strategies. However, the existing spatio-temporal hotspot analysis of traffic does not fully consider the constraints of road networks. For this reason, this study proposes a framework for analyzing the spatio-temporal evolution of traffic accidents under the constraints of road networks. First, under the constraints of road network, the spatio-temporal hotspot types are defined by comprehensively considering the spatio-temporal stability and variation characteristics of the accident hotspots. Then, the spatio-temporal evolution of traffic accident hotspots is analyzed with the case study in the city of Los Angeles, using both the road segments (sections formed between road intersections) and the fixed-length road sections (dividing a road segment into equal-length sections) as the spatial analysis units. The results show that the method of this study can identify the spatio-temporal evolution of accident hotspots in the road network context, better reveal the traffic accident risks of urban roads, and have a positive guiding significance for traffic accident prevention.</p>