Presently, nanoparticles are mixed into lubricants to enhance the lubricating and cooling properties. Some research works are available on minimum quantity lubrication (MQL) machining performance of nanofluids suspended with MoS2, Al2O3 and xGnP nanoparticles. However, the deficiency has been found in applying of metal particles like copper (Cu) nanoparticles. In this research, nanofluids have been prepared by mixing four types of nanoparticle (Cu, Graphite, MoS2 and Al2O3) into natural-77 vegetable oil with two concentrations (1 % and 2 %). Taguchi's orthogonal array has used for experimental design. The machining performance of nanofluids are evaluated with regard to the reduction in cutting force and surface roughness during MQL milling of Ti-6Al-4V alloys. Analysis of variance (ANOVA) has carried out to investigate the relative influence of machining parameters. From the analysis, Cu and Graphite nanoparticles have shown higher effects for reducing cutting force and surface roughness. The results of ANOVA have shown that the type and concentration of nanoparticles influence the cutting force significantly. The confirmation tests have carried out and found that copper-nanofluid reduced cutting force and surface roughness by 8.84 % and 14.74 %, respectively. Graphite-nanofluid reduced cutting force and surface roughness by 5.51 % and 21.96 %, respectively.