A magnetic abrasive finishing process was proposed for improving the surface accuracy of microscale -diameter STS 304 bar used in many applications such as, medical, aerospace, and nuclear industries. Most of the previous research has already explored the conventional finishing technique to improve the accuracy of material in terms of the surface roughness. However, their results are still not good enough for the requirement in the today’s engineering industry. Especially, when the workpiece is a material of microscale-diameter, use of such conventional processes becomes impossible because they entail the application of high pressures that may damage the surface to be finished. Moreover, less control is available over these conventional finishing processes. In this study, an ultra-high-precision magnetic abrasive finishing process was applied to the precision machining of microscale-diameter STS 304 bar and the experimental work are performed with many critical parameters such as, different workpiece revolution speeds, abrasive grain sizes, different finishing temperatures, and pole vibrations. The results showed that in The initial surface roughness of 0.20 μm (Ra) was decreased to 0.025 μm with 0.5 μm of abrasive grain size and pole vibration 12Hz at 40,000 rpm.