The joint of immersed tunnel is the weakest and important part, of which the mechanical performances directly affect the safety and water tightness of the whole immersed tunnel. However, there is no related study of construction condition under compressiontorsionshear combined loads. A mechanical model of joint of Honggu Immersed Tunnel is established by ABAQUS software based on 3D refined modeling technology. The mechanical performances of immersed tunnel joint under compressiontorsionshear combined loads are simulated considering nonlinear constitutive model and compared with those under compressionshear combined loads. The hyperelastic material characteristics and tightness of GINA rubber water stop tie for immersed tunnel joint are revealed by numerical simulation calculation. The horizontal loaddisplacement curve of joint under compressiontorsionshear combined loads is obtained; and the torsionshear stiffness and ultimate bearing capacity of joint are obtained consequently; it is shown that the shear strength of joint under compressiontorsionshear combined loads is smaller than that under compressionshear combined loads. Meanwhile, the mechanical performances of concrete and steel shear keys under compressiontorsionshear combined loads are obtained by local analysis. The potential destruction modes of the shear keys are predicted. The study results can provide reference for design of immersed tunnel joints of similar projects in the future.