Abstract: Intermittent wear traces were found on the ring surface of GCr15 steel pump body of a rotary blade power steering pump body after short term service and wear failure occurred. The wear failure reason of the pump body was investigated by means of chemical compositions analysis, metallographic examination, scanning electron microscopy observation and energy spectrum analysis. The results show that because blades of the power steering pump were not assembled sufficiently, which directly affected the quality of fit between the blades and the pump body, serious plastic deformative and adhesive wear appeared during the high speed rotary process of the blades.