The invention discloses a method for measuring the maximum scour depth of a viscous debris flow gully bed and the application thereof. The method comprises the following steps: weight Gamma1, depth h and a dynamic friction angle Beta of a viscous debris flow body, weight Gamma2, an internal frictional angle Phi and a viscosity coefficient C of cumulus deposits of an original gully bed, and vertical gradient J of the gully channel are determined by means of survey, measurement and sampling of the debris flow gully, testing of debris flow characteristic parameters and the like; and the obtained parameters are substituted into a calculation formula to obtain the maximum scour depth of the viscous debris flow gully bed. The method is applicable to the design of foundation embedded depth in a viscous debris flow prevention project, and the obtained maximum scour depth of the viscous debris flow gully bed serves as the minimum foundation embedded depth in the prevention project. Compared with the prior art, as the method is based on rigorous theory derivation, the maximum scour depth of the viscous debris flow gully bed can be reasonably determined, and references on the design of the foundation embedded depth in the prevention project are provided; and the method is high in result accuracy and can meet the requirements of the practical project.