Surface finishing of aluminium is a challenging task due to its soft nature and achieving nano level surface finish on aluminium surface is a daunting task even for the most advanced of the finishing processes. The material removal demands precise control of forces from these processes. Ball end magnetorheological finishing (BEMRF) process is one such process that can deliver precisely controlled forces and that too at confined and localized spaces. However, as aluminium is non-magnetic in nature it does not allow formation of an opposite magnetic pole for the process and hence the applied forces are low. To overcome this, a permanent magnet opposite pole is introduced beneath the sample surface which facilitates better forces and magnetic flux between the work surface and the tool tip. This research study is on the optimization of polishing fluid composition for the finishing of aluminium using BEMRF process. With the optimum fluid composition, the surface roughness of the aluminium sample is brought from 95.7 nm down to 53.6 nm in 32 minutes of finishing. The topographical analysis shows that the light scratches are completely removed from the surface and the deep scratches have turned into light discontinuous scratches after finishing. The finished surface is also free from the embedment of abrasive particles.