Abstract: There are a lot of large-scale loose complex Quaternary deposits originated from landslide deposits, weathering residues, alluvial and flood deposits, drifts and glacial deposits etc. prevail in the west mountainous regions of China. These multi-origin deposits of a transitional type geological-body are distinctly differing from the single-origin loose deposits in the East plain regions of China. Based on the study of contrast analysis of deposits, this paper summarizes the basic features, main types and distribution rule. Lastly, this paper analyzes the geological origin of deposits from a coupling idea, and puts forward a coupling model of the Earth's geological processes of large-scale loose deposits of river valley. The analysis shows that the large-scale complex deposits belong to multi-order, complex composite geological body of the coupling of Earth's endogenic and exogenic geological processes. This study can provide with theory evidences for environment, geological hazards and project security.