Abstract: With the development of science and technology, it has been widely applied in scientific research for the large-scale DEM(digital elevation model)with data collected in field. The use of breakline would greatly improve the quality of DEM. In this paper breakline algorithm was detailedly analyzed in the construction of regular grid DEM. The data were measured by high-precision differential GPS. The grid DEM with bounding algorithm was in the form of large-scale gully, and it was then compared with measured values and the regular grid DEM without bounding algorithm. The results indicated that the grid DEM with bounding algorithm can compare very well with the real morphology. The TIN was also constructed with the same data, and it was then converted to regular grid DEM with the same resolution. The converted DEM didn’t have better performance than the regular grid DEM. It was also found that the RMSE between measured values and interpolation results decreases with the reduction of grid spacing, which demonstrates that the regular grid DEM has gradually enhanced fitting precision for terrain with decreasing grid spacing.