Forests have multiple functions and values including ecological, economic, social and cultural aspects. The cultural value of the forest is the sum of the long-term interaction and harmonious symbiosis between human and forest ecosystem, which provides the spiritual services and cultural products of people. As an important component of the value of forest resources, forest cultural value evaluation theory and methods are still being explored and improved. Through the combination of theoretical analysis and case verification, this paper puts forward the core theory of "the symbiosis time between man and forest" and the evaluation method of forest cultural value, and constructs 8 primary indicators, 22 secondary indicators, and 53 index factors. The index weight and comprehensive index coefficient are verified, and the physical quantity and value of forest cultural value are also evaluated in this paper.The results indicate that the forest cultural value is directly proportional to the time that people stay in the forest and interact with each other. The symbiosis time between people and forest is relatively and dynamically changing; its value is closely related to the role of natural forces, forest resource elements and environmental structure. There are gradient differences in forest cultural values in different regions. The case study results of various provinces, autonomous regions and municipalities in China show that the value of forest cultural value is positively correlated with forest coverage, forest permanent population, forest quality, forest culture and natural heritage, forest recreation and forest cultural industry, and regional residents' income.