Abstract: Starting with discussing about the corresponding concepts of service function of ecosystem, and by means of Engineering Substitution Method and Market Value Method, the comprehensive service benefits of the forest ecosystem in Tonghai County, Yunnan Province were evaluated by either the direct or indirect values based on field investigation. It was showed by the results that the yearly total comprehensive service values of the forest ecosystem in Tonghai County was up to 922.31 million yuan RMB. Out of which, the benefit of water conservation was 230.27 million yuan RMB; the benefit of water purification was 39.84 million yuan RMB; the benefit of soil conservation was 52.26 million yuan RMB; the benefit of carbon sequestration and oxygen production was 33.18 million yuan RMB; the benefit of environment cleaning up was 533.78 million yuan RMB and the benefits of fruits and nuts production and recreational activities were valued as 32.98 million yuan RMB each year.