Abstract: Urban riparian zones are important ecological ecotones that integrate both wetland and urban green-space functions, serving as key interfaces for energy flow, material cycling, and biological exchange between terrestrial and aquatic ecosystems. These ecosystems provide multiple ecological services, including biodiversity conservation, water purification, microclimate regulation, flood mitigation, and recreational opportunities for urban residents. Plant diversity is widely recognized as a fundamental component supporting the ecological stability and multifunctionality of riparian ecosystems. However, under the combined pressures of rapid urbanization, hydrological alteration, landscape fragmentation, and intensive human disturbance, many urban riparian zones have experienced vegetation degradation, simplified community structure, habitat homogenization, and declining ecological functions. Understanding the composition and diversity patterns of riparian vegetation is therefore essential for ecological restoration and sustainable management of urban river systems. In this study, urban riparian zones in Shenyang, a typical northeastern Chinese city undergoing rapid urban expansion, were selected as the study area. Using a representative sampling method, 75 vegetation plots (30 m×30 m) were established across two types of riparian systems: the Hunhe River riparian zone, representing natural river systems, and artificial canal-system riparian zones. Field investigations were conducted to record vascular plant species composition and community structure in tree, shrub, and herb layers. Importance values were calculated to determine dominant species, while plant diversity was quantitatively evaluated using the Patrick richness index, Shannon-Wiener diversity index, Simpson diversity index, and Pielou evenness index. Differences in plant diversity and community structure between natural and artificial riparian systems were further compared. A total of 269 vascular plant species belonging to 171 genera and 70 families were identified. Asteraceae, Rosaceae, and Poaceae were the dominant plant families, reflecting the typical floristic characteristics of urban riparian vegetation in temperate regions. The tree and shrub layers were characterized by excessive dominance of a limited number of species, particularly Salix matsudana, Ulmus pumila, and Syringa oblata, indicating relatively low structural complexity and limited species replacement. Compared with artificial canal riparian zones, the shrub layer in the Hunhe River riparian zone exhibited significantly lower species richness and diversity indices (p<0.05). Furthermore, nearly 60% of the investigated plots showed either complete absence or strong simplification of the shrub layer, resulting in a simplified vertical community structure dominated by a ‘tree-herb’ configuration. Although herb-layer diversity remained comparatively high in both riparian types, the invasive species Erigeron canadensis was widely distributed, with an occurrence frequency of 57.33%, suggesting considerable ecological invasion risk within urban riparian habitats. Overall, the plant communities of urban riparian zones in Shenyang exhibited clear trends of structural simplification and biodiversity decline under long-term urban disturbance. To improve ecological integrity and enhance landscape resilience, management strategies such as near-natural restoration, enrichment planting with native species, optimization of multilayer vegetation structure, and invasive species control should be prioritized. The findings of this study provide scientific support for biodiversity conservation, ecological restoration, and sustainable management of riparian wetlands in rapidly urbanizing regions.