[Objective] We aim to study topographic wetness index (TWI) based on terraces digital elevation model (DEM), in order to provide basis for the study of soil water content and runoff capacity.[Methods] Using 5 m resolution DEM, 1 m resolution DEM data generated with terrace information (T-DEM) based on the real field method and 1 m resolution DEM data generated from the laser point cloud data (H-DEM), we analyzed and compared the differences among three TWIs in the terrace fields of the Loess Plateau.[Results] First, the result of 5 m resolution DEM data could show the macroscopic distribution, but it was too coarse to show the terrain feature of terrace. Second, although the 1 m resolution T-DEM data could accurately show the terrain humidity of terraced field and obviously reflect the characteristics of terrace surface and ridge feature, it showed larger deviation compared to H-DEM in the single terrace surface and the ridge.[Conclusion] T-DEM can show the distribution characteristics of the TWI in terraced fields more accurately, but it has larger deviation in terrace surface and ridge in comparison to real terrace. T-DEM's generating method need to be improved in future study.