Abstract: Based on the principles of disaster economics, forest ecological economics, especially based on the analysis method for economic losses from varied natural disasters, integrated with the basic laws of forest ecosystem in the nature reserves and the value theorem of market economy, an economic assessment index system for ecological function lose of the nature reserve ecosystem caused by frozen rain and snow disasters was set up, and the calculation method for each index was determined. Taking the forest impacted by frozen rain and snow disaster managed by Ruyang Forestry Bureau inside the Nanling Nature Reserve, Guangdong Province as an example, the economic lose from the ecological function deterioration was evaluated. It was showed by the study that the total economic lose from the ecosystem service damage to the studied forest resulted from the frozen rain and snow disaster reached 386 million RMB yuan, including 50.7794 million yuan of lose from water source conservation, 47.5044 million yuan of lose from soil conservation, 204.9124 million yuan of lose in carbon sequestration and oxygen release, 25.6002 million yuan of lose in the function of air purification, and 54 million yuan of lose in the function of ecotourism.