Aquatic vegetation and algal, as primary producers within lake ecosystems, play crucial roles in the aquatic ecosystem health. However, the combined impacts of climate warming and intensified human activities have led to significant transformations of lake environment, such as eutrophication, degradation of aquatic vegetation, and the occurrence of algal blooms. Long-term monitoring of aquatic vegetation communities and algal blooms in lakes is essential for informed decision-making on aquatic vegetation restoration and algal bloom control. This study focused on long-term changes in aquatic vegetation communities and algal blooms in Lake Changdang, a shallow lake in Taihu Basin. Based on Landsat 5 and 8 satellite data during 1985-2021, we employed the vegetation and bloom indices algorithm, a classification algorithm capable of identifying aquatic vegetation and algal blooms, to analyze the temporal and spatial evolution of floating/emergent aquatic vegetation, submerged aquatic vegetation, and algal blooms. Results showed that a significant decline occurred in both floating-leaf/emergent vegetation and submerged vegetation within Lake Changdang over the past 36 years. Particularly, submerged aquatic vegetation gradually degraded from the center towards the shore, with the coverage decreasing from 75% in 1985 to ＜21% in 2021. Since 2011, the dominant aquatic vegetation community in Lake Changdang has transitioned from submerged vegetation to floating/emergent vegetation. Notably, presence of algal blooms was first detected in 2010, with subsequent large-scale occurrences in lake center observed in 2020 and 2021. Eutrophication and enclosure activities were identified as the primary factors of the degradation of aquatic vegetation.