The invention relates to the field of research on the physical properties of sandstone of low-permeability dense sandstone reservoir, and discloses a construction method of a dense sandstone multi-scale pore model and an application. The invention provides the construction method of a dense sandstone multi-scale pore model, which comprises the following steps: (1) developing a mercury injection experiment and establishing a rock sample capillary pressure curve; (2) establishing a three-dimensional digital core by using Micro-CT scanning; (3) determining the spatial position coordinates and geometric construction characteristic parameters of the pore and simplifying the pore into pore nodes; (4) determining the communication relation among the pore nodes according to the spatial position ofthe pore nodes; (5) distributing pore throat radius, establishing an initial pore model, and then fitting the initial pore model into a capillary pressure curve; and (6) adjusting pore throat parameters and pore parameters in the initial pore model according to the actually measured capillary pressure curve. The pore model disclosed by the invention is accurate and reliable.