An intervertebral locking device comprises one spiral elastic body, two bracing mounts and two sets of locking members. The two bracing mounts are fastened respectively to both ends of the spiral elastic body. The two sets of locking members are fastened respectively with the two bracing mounts such that each set of the locking members is anchored in one of the two vertebrae adjacent to a vertebra under treatment. The spiral elastic body and the vertebra under treatment evince similar elastic qualities, i. e. similar deflection characteristics. A plurality of bone grafts affinitive to the vertebra under treatment are deposited in the chambers of the spiral elastic body and in the spaces surrounding the spiral elastic body.