Abstract：In the karst district，the collapse of overburden has been become one of major geological hazards met in engineering construction. In the light of overburden collapses occured in the three large-scale highway construction projects in Guangdong Province，the general topography configuration，engineering geology and hydrologic geology condition，and collapse circumstance of the three projects are summarized. The mechanism and cause of collapse are analyzed in detail. On this foundation，the basic condition and geology function to affact collapse are summed up. The corresponding power weight is assigned according to different factor levels. Finally，on the basis of collapse mechanism of karst overburden，the treatment measure in the practice is briefly put forward to guide practice.
