In the present study, a test rig with a low-pressure axial flow fan and a circular duct is installed to investigate the flow characteristics in the fan. The Reynolds number is 547,000 based on the blade tip velocity and blade radius. Aerodyanamic loadings are adjusted using multiple screens which have different opening areas. A particle image velocimetry (PIV) is used to measure the instantaneous flows in several cross-flow planes from the leading edge to the trailing edge of the blade. From the axial vorticity and velocity vector fields, the developments of tip-clearance flow and tip-leakage vortex are identified. For a near design condition, tip-leakage flow begins to appear at the tip-clearance region of x/R = 0.25 and travels downstream. Tip-leakage vortex moves to a neighboring blade and creats losses there.