The nondestructive detection of underground objects has long been an important problem in urban construction in that it is related to the safety of the underground objects and constructions. Based on practical applications, the authors have found that highdensity resistivity is an effective method to detect urban underground objects.The features of the resistivity image are similar to the shape of actual objects, and the interpretation is easy. Based on the exploration of such underground objects as underground pipes and canals, airraid shelters and other underground construction structures, this paper gives a comprehensive discussion on the application of highdensity resistivity to detecting the urban underground objects.