Terrain expression of loess erosional gully is the base of the researches of gully erosion modeling and prediction, which also have a great significance in related fields of geoscience. The quantitative study of gully features based on Digital Elevation Model (DEM) can contribute to the research of morphological change and formation process of erosional gully. Currently, the use of representative feature indicators to describe the morphology of loess erosional gully should be one of the most popular used methods in researches of erosional gully. However, due to the structural limitation of grid DEM, the uncertainty widely exists in the calculated results based on DEMs. In previous practical researches, it has been proved that the resolution of DEM is an important factor which can influence experimental results obviously and cause the uncertainty of feature derivatives. Especially in the area of the Loess Plateau, the fractured landform and complicated landscape elements influence the expression of morphological features. Thus, the impact of DEM's resolution are more obvious in this area. The aim of this study is to analyze the uncertainty of morphological feature expression in the Loess Plateau based on DEMs with different resolutions. In this paper, DEMs with various resolutions of three study areas in the Loess Plateau were established based on the point cloud data which were acquired by Unmanned Aerial Vehicle (UAV). Eight typical morphological indicators were selected and calculated based on DEMs. These indicators were divided into groups according to the definition of each indicator. Two groups were established to express the morphological features of gully channel and gully head respectively. The experimental results shown that DEM's resolution has great influences on morphological feature indicators of erosional gully, and the major relationships between indicators and resolutions are linear. The high development stage of erosional gully's horizontal extension can weaken the influence of DEM’s resolution on morphological feature expression. In addition, when using fixed-size windows to calculate morphological feature indicators of erosional gully, the decrease of DEM's resolution lead to the increase of actual analysis radius and then surface morphological change has a growth trend in calculation areas. This phenomenon results in the rise of gully cutting depth when using DEM with lower resolution. Besides, the main gully channel is less affected by resolution. Thus, the DEM data with low resolution can be used to calculate morphological features of main gully channel. Finally, the morphological indicators of gully head were analyzed and there are weak correlations between these indicators and the resolution of DEM.