An orbital drilling approach is proposed in machining hardened steel hole. In this study, the orbital drilling performance was investigated in connection with deburring, form error and surface roughness. First, the hole machinability of various steels was analyzed to compare an orbital drilling with a vertical drilling; then the orbital drilling experiments of hardened steel were carried out to investigate the effects of orbital drilling parameters such as tool speed, orbital feed and screw-pitch on form error and surface roughness. It is shown that the orbital drilling approach is feasible to machine the hole of hardened steel with smooth surface and little burrs using an AlTiN coating WC drill bite. Moreover, the hole form accuracy and surface roughness can be improved with increasing the tool speed and the working space, or decreasing orbital speed and orbital pitch. It is also found that the hole edge burrs can be reduced by choosing a low orbital speed. It is indicated that the form error may be greatly decreased by using a compensation approach through a new CNC tool orbital path.