The assessment of ecological damage is the basis of ecosystem protection and recovery management. Representing an original ecological level in a region, an ecosystem damage baseline is foundational in defining the degree of ecological damage. Forest soil is a key element in maintaining the chemical cycle of forest ecosystems and is also an important characterization factor in identifying the degree of damage in an ecosystem. Based on the systematic analysis of existing methods for ecological damage baselines and the characteristics of forest soil, this paper suggests several improvements to existing methods for forest soil damage baselines. We evaluated the Changbai Mountain area's deciduous broad-leaved mixed forest in Fusong County of Jilin Province as the case study. Three methods-the population distribution method, the trisection method, and the regression model method-were applied in this study. Results showed that these methods can be used successfully in determining the soil damage baseline. The baseline value determined by the trisection method was the highest while the baseline value by population distribution method was the lowest. The calculation steps for the population distribution and trisection methods were easy with results having strong comparability, and these methods were suitable in areas without substantial anthropogenic disturbance. Regression models had higher flexibility and wider application in practice. This method would be preferred in areas with sufficient data or that have experienced significant anthropogenic disturbance. If the regression model was not feasible, the other two methods could be utilized instead.