In the 21st century, with the rapid development of urban underground engineering con- struction and operation at home and abroad, sudden explosions occur frequently, causing huge casu- alties and serious property losses. This paper studies the typical explosion hazards of urban under- ground engineering, sorts out the existing classification methods of explosion hazards, and puts for- ward a classification method for typical explosion hazards of urban underground engineering. This pa- per analyzes the spatial distribution characteristics of explosive sources, and describes the possible lo- cations of sudden explosions in urban underground engineering. At the same time, this paper gives the causes of all kinds of explosions in urban underground engineering, analyzes the triggering mech- anisms and conditions of typical sudden explosions in urban underground engineering, and summariz-es the corresponding preventive measures. In this paper, the typical explosion hazards of urban under- ground engineering are identified, which expects to help enterprises and the government to take pre- ventive measures and emergency plans to reduce the incidence of explosion accidents in urban under- ground engineering.