In this study the effect and optimisation of machining parameters on surface roughness in a facing operation of Ti6Al4VELI by single point diamond machining have been investigated. The experimental studies carried under varying cutting speeds, feed rates, different tool nose radius and depths of cut. The orthogonal array, signal-to-noise ratio (S / N) and variance analysis (ANOVA) were used to examine the performance characteristics of the Ti6Al4VELI alloy turning by using single-point diamond cutting tool. The influential factors on the surface roughness after machining are feed rate and cutting speed after the conclusions revealed. Whereas the feed rate had the most significant effect on tool life. Minimal surface roughness achieved after machining is in nano-level which is better than other conventional precision machining.