This article focuses on 10 lake-reservoir type drinking water sources at the county level and above in Shangrao City，Jiangxi Province. Investigations and evaluations of water quality and phytoplankton were carried out in the spring and autumn of 2023，and a comprehensive ecological health assessment was conducted based on the survey results. The results indicate that the Shannon-Wiener diversity index of phytoplankton in the lakes and reservoirs of Shangrao City showed seasonal variations，ranging from 1.03 to 2.08 in spring and from 0.49 to 2.09 in autumn. Da'ao Reservoir and Neiwaizhu Lake had relatively high comprehensive evaluation scores of 87.46 and 84.80，respectively，and were evaluated as "very healthy"，suggesting relatively clean water quality and a stable ecosystem. Luntan Reservoir received a score of 55.45 and was rated as "sub-healthy". Muxi Reservoir and Shuangxi Reservoir had lower scores of 34.00 and 42.76，respectively，and were evaluated as "unhealthy"，indicating poor ecological conditions with risks of eutrophication and pollution pressure.