Abstract: DEM is one of the most important geospatial data.In the process of DEM construction,the fault line dealt approach affects DEM accuracy and the effectiveness of DEM-based geographic analysis results.Based on the mathematical character of fault line on the ground surface,fault lines are divided into hard and soft lines.Soft fault line is managed by modifying the weight value of sample point.Hand fault line is managed by directly dividing the sample points on both side of the line.The experiments show that this method is simple and easy to implement,and the calculation results have higher accuracy.