Abstract: A strategy was proposed to proceed the secondary fine processing when the cutting tool returned by fully taking advantage of eccentricity machining feature of orbital drilling. The effect laws of return processing parameters to machining quality and precision of the stacked materials were researched by conducting orthogonal experiments, and the resultant optimized machining parameters were determined. The experiment results show that optimized return machining process can improve hole accuracy of CFRP/Ti-6Al-4V stacks and avoid the scratch defects of the hole wall of CFRP. An average value of CFRP hole roughness decreases from R_a3.52 to R_a1.31. Less tear formation occur at the CFRP hole entry and no burrs forms at the Ti-6Al-4V hole exit.