National park tourism is a critical factor in strengthening national identity. This study explores the construction process of national identity within the context of national parks through tourists' online comments on the Three‐River Source National Park. A semiotic structure—triadic relation—is adopted to explain the signification of national park landscapes. In the first semiotic relationship, the object of the national park landscape refers to a referential symbol. Through abduction, historical associations, object‐related authenticity, and the nationalization of nature are related to each other. In the second relationship, the object in the national park landscape refers to a condensation symbol. Through induction, romantics, existential authenticity, and the naturalization of the nation are related. Finally, we identified two types of landscapes that could interfere with tourists' interpretations: disqualified landscapes and repeated stimuli. These two landscapes were created as noise. We then discuss the theoretical and practical implications of these findings.