A cable sheath of the present invention includes several adapter tubes which can be joined to one another. Each of the adapter tubes has a metal outer tube and a plastic inner tube. The plastic inner tube which is inserted into the metal outer tube abuts against the metal outer tube, so that the plastic inner tube of each of the adapter tubes can be used for receiving a metal cable therein. Thereby, said invention can receive a brake cable or the like without a plastic tube of the cable, so that said invention can prevent the cable from being wound by a remaining interior stress from the plastic tube.