Abstract: The Design of soil-nailing prop-up under complex conditions near civil defence passage is introduced. In order to ensure the safety of civil defence engineering, the analysis software of FLAC geotechnical engineering commonly used in the world is adopted to compare and optimize the design schemes and to predict the deformation of the protection and the internal force of the soil nail. The comparison analysis among the measured data, the theoretical calculation value and the numerical simulation value shows that the exerted force on the soil nail is obviously lower than the calculated results by conventional calculation method and slightly bigger than the results of FLAC numerical simulation. The feasibility of applying FLAC to analyze the protection deformation and internal force of soil nail are demonstrated. At the same time, the defects of the present calculation method are pointed out.