The hydraulic characteristics in an open channel with vegetation are very important in controlling the environment pollution and restoring the river ecology. This paper studies the influence of the bed form and the vegetation patch density on the spatial velocity pattern. Rigid fiberglass circular cylinders are used to simulate the vegetation and a 3-D acoustic Doppler velocimeter (ADV) is used to measure the local flow velocities. Two types of bed forms and a series of vegetation patch densities are considered. The experimental results show that the bed form significantly influences the vertical distribution of the streamwise velocity. Besides, the velocity is affected by the bed form while the lateral distribution shape of the streamwise velocity as well as the lateral and longitudinal distribution shapes of the depth-averaged velocity is less affected. When all test conditions but the bed condition remain the same, as a result of the water energy consumption by the sediment movement, the velocity in the mobile bed case is smaller than that in the rigid bed case. The vegetation patch density has a significant effect on the flow velocity. The distributions of the flow velocity at different locations show different trends with the increase of the vegetation patch density. The upstream adjustment length is not affected by the vegetation patch density, but the steady wake length is very much affected.