This study investigates the machining properties of Al6061 reinforced with boron carbide (B4C) and the effect of cutting parameters on surface roughness in wire electrical discharge machining of (WEDM). Four Al 6061 metal matrix composites reinforced with 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.% B4C were fabricated by powder metallurgy. Influence of the B4C reinforcement particles on surface roughness were studied during the WEDM. Experiments were conducted based on Taguchi L-18 (2(1) x 3(2)) with a mixed orthogonal array and the optimal machining parameters were investigated for the surface finish. The machining parameters were analyzed by using main effect graphs and analysis of variance (ANOVA). The results showed that the reinforcement particles were uniformly dispersed in matrix structure and the surface quality of machined specimens were improved with increasing the weight fraction of the B4C reinforcement. The best surface roughness values were measured at lower peak current (IP) and surface quality of the machined part was decreased with increasing peak current.