Abstract: Sand abrasion in fluid machinery remains at the exploratory stage in spite of tremendous previous efforts in experimental, numerical and theoretical studies in recent years. This paper presents a preliminary study on sand abrasion in centrifugal pump from the perspective of turbulent coherent structure in near-wall region. We derive the near-wall sand velocity normal to the wall using the BBO equation of sand motion, and obtain the sand velocity along the local flow in a sweep considering the behaviors of burst structure. Then, we can calculate the impact angle of sand particles on the impeller surface of a centrifugal pump. The results show that in a centrifugal pump, the small angle cutting damage of small sand particles to impeller surfaces is caused by the sweep of coherent structures in near-wall turbulences. This conclusion is supported by previous experimental tests in literature.