Abstract: Evaluating the value of biodiversity conservation in the state-owned forest farms can provide a basis for the performance management of forest farms. Based on the study of the types of rare and endangered animals and plants as well as the ancient tree resources in Huading Forest Farm of Tiantai County, the biodiversity service value of the forest farm was evaluated in accordance with the "Assessment Specification for the Service Functions of Forest Ecosystems". The results showed that: it has been found that there were three and two species of national first- and second-class key protected wild animals in Huading Forest Farm in Tiantai County, and there were one and eight species of national first- and second-class key protected wild plants, respectively. Huading Forest Farm was rich in ancient tree resources, with 58 species and a total of 3757 ancient trees. Among them, there were 63 first-class protected ancient trees with the age ≥ 500 years old, accounting for 1.7%; there were 227 second-class protected ancient trees aged 300-499 years old, accounting for 6.0%; and there were 3 467 third-class protected ancient trees aged 100-299 years old, accounting for 92.3%. The Shannon-Wiener diversity index of forest in Huading Forest Farm was 11.4, and the index ranking was Grade 1. The annual conservation value of forest biodiversity per unit area was 50 000 yuan·hm⁻², with a total value of 166.19 billion yuan.