A sacral prosthesis, comprising: a prosthesis main body, the prosthesis main body comprising two first prosthesis bodies and a second prosthesis body connected between the two first prosthesis bodies, a first end of each of the first prosthesis bodies being connected with the second prosthesis body, the two first prosthesis bodies and the second prosthesis body being of an integrally prototyped structure, a second end of each of the first prosthesis bodies being extended along a direction far away from the second prosthesis body, and being contacted and matched with an ilium, and a top of the second prosthesis body being contacted and matched with a lumbar vertebral body; and a screw-rod structure, the screw-rod structure comprising a connecting seat and a rod body, the connecting seat being connected with the prosthesis main body, and the rod body being fixed on the connecting seat, wherein a first screw hole is formed in at least one of the first prosthesis bodies; the first screw hole is conical hole; a first screw seat is arranged in the first screw hole; and the first screw seat is provided with a spherical inner surface; and/or a second screw hole is formed in the second prosthesis body; the second screw hole is a conical hole; a second screw seat is arranged in the second screw hole; and the second screw seat is provided with a spherical inner surface; an anti-dropping mechanism is arranged on the prosthesis main body; the anti-dropping mechanism is arranged between the prosthesis main body and the connecting seat in a clamping manner; and the anti-dropping mechanism comprises a first anti-dropping tentacle matched with a screw accommodated in the screw hole; wherein the anti-dropping mechanism further comprises an anti-dropping main body; the anti-dropping main body is arranged between the prosthesis main body and the connecting seat in a clamping manner; the anti-dropping mechanism further comprises a second anti-dropping tentacle; the first anti-dropping tentacle and the second anti-dropping tentacle are connected with the anti-dropping main body and are extended outward; and a limiting sleeve matched with the rod body is arranged on the second anti-dropping tentacle. a prosthesis main body, the prosthesis main body comprising two first prosthesis bodies and a second prosthesis body connected between the two first prosthesis bodies, a first end of each of the first prosthesis bodies being connected with the second prosthesis body, the two first prosthesis bodies and the second prosthesis body being of an integrally prototyped structure, a second end of each of the first prosthesis bodies being extended along a direction far away from the second prosthesis body, and being contacted and matched with an ilium, and a top of the second prosthesis body being contacted and matched with a lumbar vertebral body; and a screw-rod structure, the screw-rod structure comprising a connecting seat and a rod body, the connecting seat being connected with the prosthesis main body, and the rod body being fixed on the connecting seat, wherein a first screw hole is formed in at least one of the first prosthesis bodies; the first screw hole is conical hole; a first screw seat is arranged in the first screw hole; and the first screw seat is provided with a spherical inner surface; and/or a second screw hole is formed in the second prosthesis body; the second screw hole is a conical hole; a second screw seat is arranged in the second screw hole; and the second screw seat is provided with a spherical inner surface; an anti-dropping mechanism is arranged on the prosthesis main body; the anti-dropping mechanism is arranged between the prosthesis main body and the connecting seat in a clamping manner; and the anti-dropping mechanism comprises a first anti-dropping tentacle matched with a screw accommodated in the screw hole; wherein the anti-dropping mechanism further comprises an anti-dropping main body; the anti-dropping main body is arranged between the prosthesis main body and the connecting seat in a clamping manner; the anti-dropping mechanism further comprises a second anti-dropping tentacle; the first anti-dropping tentacle and the second anti-dropping tentacle are connected with the anti-dropping main body and are extended outward; and a limiting sleeve matched with the rod body is arranged on the second anti-dropping tentacle.