Abstract: Aquatic floating vegetation usually can be found in natural rivers,and it decreases the discharge capacity of rivers. Furthermore, it changes the flow structure and causes the flow status more complicated. To explore the characteristics of flow under the action of floating vegetation group, rigid floating vegetation is simulated by using cylindrical glass rods with a diameter of 0.01m, particle image velocimeter（PIV） and wireless ultrasonic water level measuring system are used to measure water level and flow velocity. Water flow characteristics affected by the vegetation root into water, vegetation layout and vegetation density on are investigated by using experimental tests in a laboratory flume.Experimental results show that the floating vegetation group has a great effect on the flow structure in the channel. After the float vegetation group is set in the cannel, the maximum flow velocity occurs at the center between the vegetation roots and the flume bed. The maximum turbulent kinetic energy appears near the vegetation roots and the channel bed, while the minimum turbulent kinetic energy appears near the center between the vegetation roots and the channel bed. The length of the floating vegetation in the water affects the water level distribution in the channel. Both the water level and water surface slope along the way at the upstream of the vegetation area grow with the increase in the length of the vegetation in the water. Furthermore, vegetation layout affects the transverse distribution of the flow velocity at the downstream of the vegetation area. The same side layout of the floating vegetation groups in the flume causes the phenomenon “strengthening effect” for flow velocity at the downstream of the vegetation area, i.e. the flow velocity at the downstream of the vegetation area becomes greater. Similarly, the staggered layout of the floating vegetation groups in the flume causes the phenomenon of “weaning effect” for flow velocity at the downstream of the vegetation area, i.e. the flow velocity on the downstream sides becomes smaller. The strongest turbulent kinetic energy occurs at the boundary between vegetated area and non-vegetated area. In addition, the vegetation density also affects the flow velocity and turbulence intensity distributions. With the increase in vegetation density, the variation amplitude of the flow velocity in the vegetation area grows, while the turbulence intensity decreases. Under the floating vegetation groups, the flow velocity grows with the increase in vegetation density, and above the floating vegetation groups’ root, the flow velocity decreases with the increase in vegetation density. In the vegetation area, the flow velocity shows an S-shaped distribution along vertical direction.