Vegetation is of great importance in hydraulic engineering as it can affect the flow structures of compound channels in many ways, including the velocity profiles, momentum exchange, and shear stress distributions. This complex flow structure in vegetated compound channels has attracted more and more research interests. However, most of the previous studies have been focusing on fully-covered vegetated compound channels, there are little studies on compound channels with partially vegetated floodplain. This research carried out novel experiments to investigate the flow structure of compound channels with partially-covered vegetation on the floodplain. The results showed that the discharge of the main channel decreases as the depth ratio increases. The retardation effect of vegetation on the flow of non-vegetated floodplain region decreases with the increasing water depth. In addition, the vertical velocity profile in the vegetated zone performs differently in various depth ratios, with its velocity taking a maximum around the middle-water depth zone under emergent cases, while being the maximum near the free surface under submerged cases.