National forest parks are important ecotourism destinations for locals and out-of-town visitors worldwide. The increase in protected areas is accompanied by challenges. The major challenge is the tension between conservation and exploitation. However, over-exploitation is causing irreversible damage to tourism resources by neglecting to accelerate conservation and satisfying the needs of only tourists. Therefore, it is a prerequisite to evaluate the value of ecotourism resources, especially non-use values. Liugong Island National Forest Park is a seaside forest park in Shandong Province, China. Tourist activities have negatively impacted the amenity and values of the park and increased management and maintenance costs. This study aimed to enhance the protection awareness of ecotourism resources by evaluating non-use values with the contingent valuation method (CVM). Ecotourism attitude factors were extracted by factor analysis, and the ecotourism market was segmented by cluster analysis. Then, an empirical assessment model was designed. Furthermore, through a double-bounded dichotomous choice model of the CVM, non-use values of ecotourism resources were estimated, and differences in non-use values among the groups with different attitudes were discussed. The results indicated that (1) Tourists with conservation backgrounds tended to pay more for general non-use values, while high-income tourists were willing to pay more for the Altruistic value; (2) The willingness to pay (WTP) of tourists was highest for the Bequest value, followed by the Existence value or Altruistic value, and finally the Option value; (3) The WTP was highest for the group valuing pluralism, followed by the group concerning resources, and lowest for the group concerning the environment. This study can provide valuable information for ecotourism planning and management that corresponds to current issues and tourist needs.