Over the last few decades, small and medium - sized lakes in Yunnan have experienced increasing stressors derived from anthropogenic disturbances and regional climate change, and the deterioration of water quality and the loss of ecosystem resilience. In the context of absent or insufficient monitoring data, it is urgently needed to uncover the ecological responses to environmental changes over a decadal to centennial timescale in these lakes. Here we applied sediment records from Jianhu Lake( 26°25.0'~26°31.5'N,99°55.0'~ 99°59.5'E) from the northwest part of Yunnan Province,which is a medium-sized (lake area = 6.23 km~2) and shallow (mean depth = 2.7 m) system with an altitude of 2188 m a.s.l. and a catchment area about 918 km~2. A 31-cm long sediment core was taken from the deep basin(26°29'29.94"N, 99°56'11.15"E; water deep in 5.2 m) using a gravity corer. The top 5 cm of the core was extruded at 0.5-cm intervals with the core below 5-cm depth sectioned at 1-cm intervals, resulting in a total of 36 sediment samples. The ~(210)Pb and ~(137)Cs radioactivity profiles showed that the sediment core spanned the last ca. 200 years (ca. 1830~2013 A. D.). Diatom and multiple proxies(i.e. LOI_(550)(loss on ignition), grain size, carbon and nitrogen elements and stable isotopes) from the sediment core were analysed to reconstruct the environmental change history and to uncover the temporal pattern of diatom responses in Jianhu Lake. A total of 64 diatom species belonging to 32 genera were identified throughout the core, including 21 species with a relative abundance > 5% . The dominant species included Nitzschia angustata, Cyclostephanos tholiformis, Aulacoseira granulata,Cyclotella pseudostelligera, Gyrosigama acuminatum and Cocconeis placentula. The diatom species richness decreased steadily from 45 to 26 over time, with a long-term decline in the percentage of benthic diatoms. The sediment grain size records indicated a weakening trend of hydrodynamic conditions due to lake regulation. The increasing concentration of total nitrogen (TN) indicated a trend of nutrient enrichment during the past two centuries, with an accelerating trend observed since ca. 1990. Increased lake productivity and algal production was reflected by the increased LOI_(550) level and a depletion of delta ~(13)Cbulk signal over the last two decades. The results of Redundancy Analysis (RDA) showed that hydrodynamic conditions and the nutrient level were among the key environmental factors in driving diatom community variation over the last two centuries. Furthermore, variance partitioning analyses showed that hydrodynamic conditions and the nutrient level independently accounted for 6.3% and 1.4% of the total variance in diatom variation, respectively, with their interaction explaining 13.1% of diatom variation since ca. 1830 A. D. More recently, the stronger interaction among nutrient, hydrological and temperature proxies revealed an important role of regional warming in driving diatom community shift. Overall, the decrease in ecosystem health and biodiversity has been prominently caused by intensified human disturbances in the context of climate change over the last two centuries. Therefore, the control of catchment nutrient input and appropriate water regulation should be required for the maintenance of ecosystem health in plateau shallow lakes under the scenario of long-term climate change.