Abstract: Three-dimensional turbulent flow of the endwall region inside a centrifugal compressor impeller was studied using a Laser Doppler Velocimetry.The flow was surveyed across the entire passage at seven radial locations (leading edge to trailing edge) and ten axial locations.Data obtained include three-dimensional mean and turbulent characteristics.The measurement results indicated that a corner vortex existed along the suction surface near the endwall,leading to obvious flow blockage and turbulence.The suction-side horse-shoe vortex of the blade leading edge developed towards the pressure surface with the flow downstream,resulting in the flow mixing between the endwall boundary layer and the main flow.Interaction of the two sides of the horse-shoe vortex occured at the corner of the pressure surface at about half chord,causing more flow blockage and turbulence.The variations of axial,tangential and radial turbulence intensities were similar,and the tangential turbulence intensity was the highest of the three components.