The salt damage is a common problem at earthen sites. There are serious phenomena of the salt damage on the surface of Jinsha earthen site. Research on the distribution and evolution of the salt damage is the first step toward a science-based strategy to protect Jinsha earthen site, and also a prerequisite for further exploring the pathogenic mechanisms of the salt damage. In this study, we collected the existing investigation data of Jinsha earthen site from 2010 to 2020 and conducted qualitative and quantitative analyses of the type, distribution characteristics and evolution process of the salt damage at the site using the on-site investigation and image processing technology. The results show that the main types of the salt damage at Jinsha earthen site include salt efflorescence, crisp powdering, hollowing, peeling and erosion. The main distribution areas are near the northwest corridor and ancient river channels, and the sidewalls of machine-dug pits present the most serious damages. From top to bottom, the salt damage transition from salt efflorescence to single crisp powdering, then hollowing and peeling and finally erosion at the bottom layer. In later stages of all types of the salt damage, distribution ranges become larger, development rates become faster and damage degrees of earthen sites become greater. Distributions of soluble salt contents along the height are not only related to the capillary rise, but also related to the development process of the salt damage.