The invention discloses an LNG storage tank for a diesel-LNG hybrid power ship. The LNG storage tank comprises a sealed shell and a sealed inner container arranged in the shell, wherein the shell is provided with a first LNG filling pipe communicated with the bottom of the inner container; the inner container is supported in the shell through a plurality of glass steel pipe struts, and a heat insulation layer is wound on the inner container; an interlayer between the shell and the inner container is vacuum; the middle part of the inner container is provided with a wave-proof device; the wave-proof device comprises a central pipe and a support plate; the axis of the central pipe is superposed with the axis of the inner container; and the support plate is trumpet-shaped, an opening at the small end of the support plate is welded with the outer circumference surface of the central pipe, and an opening at the large end of the support plate is welded with the inner wall of the inner container. Because the wave-proof plate with a special structure is arranged in the inner container, impact and oscillation of liquid in the tank body in each direction when the ship runs are reduced, and the safety is ensured. Meanwhile, the LNG storage tank provides proper liquid storage volume and good heat insulation performance, and is fully suitable to be used in the ship.