As a critical water conservation area in the Yangtze River Delta and the headwaters of the Qiantang River, Qianjiangyuan National Park holds significant ecological importance. Compared with other biological indicators, periphyton can more accurately indicate the health status of the local aquatic ecosystem. This study, utilizing periphyton as the research subject, assessed the ecological health of Qianjiangyuan National Park through both the Periphyton-based Biotic Integrity Index (P-IBI) and periphyton biological status evaluation. The results from these two methodologies consistently demonstrated that the park's ecological health is at a moderate level. While the findings provide a scientific basis for ecological conservation, the P-IBI method may oversimplify ecosystem complexity due to its limited scope. Future assessments should adopt integrated evaluation frameworks that synergistically analyze both biotic communities and abiotic factors to achieve holistic ecosystem health certification.