The present invention provides an iliac prosthesis, comprising: a prosthesis main body (10), the prosthesis main body (10) being of an arched structure, the prosthesis main body (10) including a first end portion (11) contacted and matched with a sacrum (1) and a second end portion (12) contacted and matched with an acetabulum (2), a first screw hole (111) being formed in the first end portion (11), the first screw hole (111) being conical hole, a first screw seat being arranged in the first screw hole (111), and the first screw seat being provided with a spherical inner surface； a screw-rod structure, the screw-rod structure including a connecting seat (22) and a rod body (23), the connecting seat (22) being connected with the prosthesis main body (10), and the rod body (23) being fixed on the connecting seat (22)； and an anti-dropping mechanism (30), the anti-dropping mechanism (30) being arranged between the prosthesis main body (10) and the connecting seat (22) in a clamping manner, and the anti-dropping mechanism (30) including a first anti-dropping tentacle (31) matched with a screw accommodated in the first screw hole (111). The technical solutions of the present invention can effectively solve the problems of unreliable supporting and easy fatigue break of the screw-rod system in the related technology.
