The traditional solid alumina abrasive has been widely used in commercial slurries. But it is easy to cause polishing scratches due to its dense solid structure. The morphology of the abrasives can also impact on the chemical mechanical polishing (CMP) performances. To improve the CMP performances of the hard disk substrate, rods-like porous alumina and flower-like porous alumina abrasives were prepared and their chemical mechanical polishing behavior investigated. The results showed that the porous alumina abrasives with different morphologies exhibited lower topographical variations and surface roughness than solid alumina abrasives under the same testing conditions.