This research is devoted to study the effect of ball milling technique to improve the surface hardness of carbon steel (CK 45) die guides. This process depends on a rotating cylinder with number of certain size steel balls. Experimental works are carried out on guides rods with (15 mm) diameter, and (35 mm) length processed on laboratory ball mill. The factors those studied in this process are rotating speed, and time. The surface hardness is recorded before and after the processing. The results show that the best surface hardness is (86.11 Hv) obtained with ball size (5 mm) diameter rotate with (30 rpm) for (90 min.) processing time.