• Solid particle erosion (SPE) are analyzed combined with rebound effect. • Erosion degree caused by rebound is less than that caused by particle first impact. • When the axial clearance increases, erosion area extends to the front of rotor blade, but erosion degree decreases. • Influence trend of axial clearance on SPE and stage efficiency is different. Based on the steam-solid two-phase flow model combined with rebound effect, the influence of axial clearance on the solid particle erosion (SPE) characteristics and efficiency in ultra-supercritical steam turbine governing stage was analyzed. The results show that the erosion damage degree caused by rebound is less than that caused by the particle first impact. With the increase of axial clearance, the number of particles rebounding back to the trailing edge of the suction surface(SS) in nozzle decreases. When the axial clearance increases, the large size particle impact velocity and impact angle move towards the leading edge of rotor blade, and the erosion area extends to the middle and front of the pressure surface (PS), resulting in the increase of erosion area. However, the particle impact angle deviates from the serious erosion angle, and the erosion degree decreases. The axial clearance has different influence trends on SPE and stage efficiency. With the increase of axial clearance, the erosion rate density decreases continuously, about 59.2%, but the stage efficiency increases first and then decreases. So the influence of SPE and stage efficiency should be comprehensively considered for the selection of axial clearance.