Burnishing is a post machining process that is traditionally used to impart specific physical, mechanical properties on surfaces. Optimization of surface microhardness using Taguchi orthogonal array L25 is reported in the present study. The material selected for the experiment is aluminum alloy 63400 grade. Carbide roller burnishing toolis used in the experiment. The factors that are controlled are speed, feed, depth of penetration and number of passes.Surface roughness tester SURFTEST SJ-210is used to measure a surface roughness. In the present investigation for analyzing the data, plot of average response curves, plot of signal to noise ratio(S/N), responsegraphs and analysis of variance (ANOVA) for S/N data is used. Depth of penetration and feedare the most contributing factors in surface roughness. Optimum condition from Taguchi analysis is speed 27m/min, 0.5mm/rev feed, depth of penetration 0.06mm and number of passes two.