Global digital elevation models (GDEMs), the three dimensional digital cartographic representation of the Earth topography, have a crucial impact on many geo-spatial analyses. In these days, recently released ALOS World 3D 30 m (AW3D30) and 1 arc-second (~30 m) Shuttle Radar Topography Mission (SRTM) C-band GDEMs are very popular and widely in demand by scientific community. In this paper, we comprehensively analysed the coherence level of these GDEMs in country-scale calculating and interpreting the influence of terrain inclination and land cover classes. The coherence between two GDEMs was estimated by model to model accuracy analysis and height-scaled colourful coherence map based on differential of GDEMs. The results demonstrated the significance of ascending and descending orbits, terrain inclination and land cover on the coherence level of AW3D30 and SRTM GDEMs clearly.