Abstract: There were 33km lines in the karst development area of the Guang-Qing Expressway expansion project. There have been many karst collapses during the construction of the area. The formation of karst collapse is due to the stress of rock and soil greater than the resistance to collapse. Different types of collapsing stress may cause diverse mechanical effects, which constitute varieties of collapsing modes. Based on the analysis of climate, topography, geological structure, hydrogeological conditions of the Guang-Qing highway and so on, the formation mechanism and catastrophe mode of karst collapses during construction are discussed. It is pointed out that rainfall and construction technology are the main inducing factors for karst collapse. The main catastrophe modes are analyzed in detail during the construction process, including the submerged model, the vibration mode and the load mode. The methods of preventing and dealing with these collapse modes are proposed. The analysis results can provide a reference for the prevention and treatment of collapse in karst areas.