The invention relates to the field of building anti-floating, in particular to an emergency basement anti-floating structure and a construction method of the emergency basement anti-floating structure. The emergency basement anti-floating structure comprises a pressure relief hole penetrating a basement bottom plate layer and a cushion layer in emergency and a water conduit used for underground water diversion, and the water conduit is externally connected with a drainage pipe. The basement bottom plate layer comprises a waterstop hole located in the upper portion of the pressure relief hole. A filtering body is wrapped by the bottom end of the water conduit. The bottom end of the water conduit and the filtering body are inserted into the pressure relief hole and communicate with underground water, a gap between the peripheral face of the water conduit and the pressure relief hole is filled with a plugging object to form sealing, and a valve is arranged between the water conduit and the drainage pipe, located in the waterstop hole without being exposed and detachably connected with the drainage pipe. The construction method includes the steps that the pressure relief hole is directly formed and used for underground water pressure relief and basement backfilling for increasing the load, after the water level is returned to the original state, the waterstop hole is formed, and the water conduit is inserted into the pressure relief hole to communicate with the underground water; and after basement top plate soil covering construction is completed, and the waterstop hole is filled with expansive concrete. The emergency basement anti-floating structure and the construction method are suitable for emergency basement anti-floating.