To investigate the effect of abrasive agglomeration on the wear behavior of optical glasses during magnetorheological finishing， this study used an environmentally controlled linear reciprocating tribometer to conduct friction and wear experiments of fused silica by rubbing against a stainless steel sphere and adding different degrees of agglomerated nanodiamond polishing solution. Optical microscopy and a white light interferometer were used to characterize the wear mechanism of the fused silica， and the tribological results were compared with those of actual magnetorheological polishing. Experimental results showed that the material removal rate （MRR） and subsurface damage of the fused silica increased with the degree of nanodiamond particle agglomeration. When the load was 0.5 N， the wear mechanism of the fused silica was domihnated by adhesive and abrasive wear， and no dissemble subsurface damage was found beneath the wear track of the fused silica. When the load was increased from 0.5 to 4 N， the wear mechanism of the fused silica was dominated by abrasive wear， and substantial surface and subsurface damage were found. Both the tribological experiments and magnetorheological polishing were conducted with polishing fluids having the same degree of abrasive particle agglomeration， and results showed that the MRR of the fused silica under the two methods was nearly the same. This indicated that the tribological test could be used to predict the MRR in actual magnetorheological polishing to a certain extent.