The utility model discloses a combined
drill bit which comprises a
tool bit, a
drill handle and a
drill rod which are coaxially and integrally connected, the
tool bit is coaxially fixed at the other end of the drill rod, a first discharging groove is formed in the side face of the
tool bit, a second discharging groove matched with the first discharging groove is formed in the drill rod, and a receding groove and a
cutting face which are connected with each other are arranged on the side face of the tool bit. The
cutting face is arranged between the receding groove and the first discharging groove, the
diameter of the
cutting face is larger than that of the bottom of the receding groove, and the
diameter of the bottom of the receding groove is not smaller than that of the drill rod. The receding groove and the cutting face are arranged on the tool bit, the
diameter of the cutting face is larger than that of the bottom of the receding groove, and the diameter of the bottom of the receding groove is not smaller than that of the drill rod, so that in the
machining process of the
drill bit, the drill rod cannot make contact with the hole wall of wood,
friction force does not exist between the drill rod and the hole wall, and heat generated in the use process of the
drill bit can be effectively reduced; and the
processing quality can be ensured.