Abstract: National parks hold significant value and meaning within the global ecological protection system. Understanding public perception and attitude toward national park construction and ecological conservation serves as an essential reference for future directions. With the rapid rise of social media, the public is increasingly engaging in discussions about ecological protection topics. Particularly, comments on authoritative documentaries provide insights into public attitudes and sentiments toward national park construction. This study analyzes comment data from the documentary Our National Parks, produced under the guidance of the National Forestry and Grassland Administration (National Park Management Bureau). It employs TF-IDF keyword extraction, BERTopic topic modeling, and large language model sentiment analysis to explore public awareness, emotional responses, and attitudes toward China′s national park construction. The findings indicate that biodiversity conservation, the construction of the national park system, and harmonious coexistence between humans and nature are focal points of public concern. In terms of public sentiment, most comments express strong support for ecological protection measures, specific species preservation (such as giant panda and Siberian tiger), and natural landscapes. However, some negative comments reveal public concerns about the imbalance between resource utilization and the strength of environmental protection efforts, questioning issues like "mountains of garbage". Some comments also focus on the restrictions of recreational facilities within national parks, highlighting conflicts between tourists and environmental groups over resource development and ecological protection. These negative sentiments offer targeted insights for policy making, especially when balancing ecological conservation with economic development. By analyzing sentiment and extracting topic from social media comments, this study uncovers public attitudes towards national park construction. It provides new perspectives and empirical evidence for optimizing future ecological protection policies, formulating public communication strategies, and advancing related academic research.