The invention discloses a syringe driving mechanism and an injection pump, wherein the syringe driving mechanism comprises a stand, a sliding base, a split nut, a press block, a push rod and a screw rod which is arranged in a mode of being parallel with the push rod; the stand comprises two end plates and a guide component; the split nut is meshed with the screw rod; a driven piece and a limiting part are arranged on the peripheral wall of the split nut; the driven piece is connected to the sliding base in a rotatable mode; a rotating shaft of the driven piece is parallel with the screw rod; the press block is connected to and arranged on the sliding base; the press block is elastically propped against the limiting part; a clamping part, which is clamped and matched with the limiting part, is arranged on the press block; the sliding base is movably sleeved on the push rod, and the push rod is capable of undergoing a spinning motion relative to the sliding base; a driving piece, which is transmitted and matched with the driven piece, is arranged on the push rod, and the driven piece is rotated by the driving piece when the push rod is rotated; and the split nut is completely separated from the screw rod when the limiting part is clamped into the clamping part. Through the technical scheme of the invention, a phenomenon that the split nut and the screw rod are ground in an operation of adjusting the position of a push head, so that the safety of the injection pump is guaranteed.