Abstract: Based on the concept of effective abrasive grain number and the calculation method of surface roughness, two indexes, namely effective dressing rate N_r and dressing dispersion degree H, were proposed to evaluate the grinding performance and surface topography of the grinding head. The variation of N_r and H during the dressing process were analyzed. The relationship between both indexes and the surface roughness and the grinding force of carbon fiber reinforced plastics(CFRP) after grinding was also established. The experimental results show that N_r can effectively characterize the dressing state of the abrasive particles on the grinding head and reflect the passivation degree of the grinding head. H can effectively characterize the contour of the abrasive grain, and predict the quality of CFRP surface. When H is 18~25 μm, the grinding head surface roughness is the best. The grinding head force has smaller growth amplitude, and the grinding head has better performance.