Mountain disasters occur mostly in mountainous areas with steep slopes. Most mountainous areas are ecosystems with a relatively stable ecosystem structure and bear important regional ecological service functions. Mountain disasters destroy the components of the ecosystem of the affected area, which in turn affects the structure, function and health of the ecosystem. This study takes the forestry unit as the basic unit, mountain disasters as the risk source, and Nanling’s various natural ecosystems as the risk receptors. Based on the mechanism of mountain disasters and the interaction mechanism between mountain disasters and ecosystems, the risk of mountain disasters, the vulnerability of risk receptors and the variability of ecosystem responses were evaluated in Nanling on the small-scale forestry scale.