<p>Understanding diatom community similarity between surface sediments and littoral macrophytes is essential for assessing the ecological connection between offshore and littoral zones of lake ecosystems. This study investigated water quality and diatom communities in surface sediment and littoral macrophyte samples of 36 mountain lakes in central China, in order to explore environmental drivers of diatom community similarity between surface sediments and littoral macrophytes. Correspondence canonical analysis revealed that Ca²⁺, K⁺, and the ratio of Secchi depth to water depth (SD/WD) were three significant variables influencing surface sedimentary diatom distribution, while K⁺ and TP were two significant variables accounting for epiphytic diatom distribution. Generally, high light penetration can promote macrophyte growth and hence increasing the contribution of epiphytic species to surface sedimentary diatoms in high-elevation lakes. High cation concentrations in low-elevation lakes probably stimulated the proliferation of planktic species. Diatom community similarity between surface sediments and littoral macrophytes ranged from 0.18 to 0.53, and it was negatively correlated with K⁺, but positively correlated with the elevation and SD/WD. The results suggest that epiphytic species can be an important source for sedimentary diatoms, advancing our understanding of the ecological connection between littoral and offshore zones.</p>