The invention discloses a drill rod retaining mechanism, which comprises a rotating sleeve, wherein multiple slip pieces are matched in taper to form a structure with an adjustable clamping diameter in the sleeve; transverse pins are fixedly connected to the outer walls of the slip pieces in a screwing manner; one end of each transverse pin penetrates through a sleeve wall of the sleeve and has an exposed section exposed from the sleeve wall; an elastic element is arranged between the sleeve and the slip pieces, and is used for driving the slip pieces to move towards a clamping diameter reduction direction; an axial sliding chute in sliding fit with the transverse pins is formed in the sleeve wall of the sleeve; a nut is also screwed to the sleeve, and is used for driving the slip pieces to move towards a clamping diameter increasing direction through the transverse pins; preferably, the nut is connected with a sliding sleeve through multiple salient points; the multiple transverse pins are connected to the same sliding sleeve through the exposed sections, and the exposed sections form sliding fit connection with matching holes in the sliding sleeve. The drill rod retaining mechanism has the beneficial effect that the condition that a drill rod slides down and moves backwards to hurt a person or potential safety hazards of equipment can be effectively avoided.