The invention discloses a bone grafting instrument for use in bone grafting surgery. The bone grafting instrument comprises a delivery tube. A filling orifice communicating with the inner cavity of the delivery tube is formed in a portion, near the end, of the peripheral wall of the delivery tube, and a pushing mechanism is detachably disposed on the delivery tube by means of a connecting piece. In the bone grafting instrument provided in the invention, the pushing mechanism is disposed to be detachable from the delivery tube. Thus, when flushing a bone grafting cavity, the delivery tube and the filling orifice are used as a flushing appliance without installing the pushing mechanism on the delivery tube first. When filling the bone grafting cavity, the pushing mechanism is installed on the delivery tube, and then a filler is added to the filling orifice in the delivery tube and pushed into the bone grafting cavity by the pushing mechanism, thereby completing filling of the bone grafting cavity. The bone grafting instrument is simple in structure, and has two purposes as one single instrument such that the surgical operation of bone grafting becomes simple, thereby reducing the difficulty of the bone grafting surgery, reducing the number of instruments used in the bone grafting surgery, and lowering the cost of the bone grafting surgery.