Abstract: The flow measurements of part-span stall were accomplished in an axial flow fan test.The measurements include laser anemometer measurement of the stall cell in the mean flow with an ensemble averaging technique and instantaneous flow measurement with hot-wire and flow visualisation technique.The mean flow field measurement indicates that the stall cell appears mainly in the front of the rotor,while the flow field in the tip region of the rotor features essentially the cross blockage of the tip clearance flow.The instantaneous flow measurement shows that the kinetics of the stall cell can be described by using two fundamental concepts of dipole.