Steel hollow box gravity anti-floating device suitable for cast-in-place flat slab

The utility model provides a steel hollow box body gravity anti-floating device suitable for a cast-in-place flat slab, and belongs to the technical field of hollow box body anti-floating devices. The problems that due to the flow state property of concrete, a hollow box floats upwards, if light, the elevation of a local floor is ultrahigh, the thickness of a decoration method is reduced, if heavy, large-area and large-amount floating is caused, and quality accidents occur are solved. The liquid injection device comprises a hollow box body and liquid injection pipelines, the liquid injection pipelines comprise at least one main liquid injection pipeline and a plurality of auxiliary liquid injection pipelines branched by each main liquid injection pipeline, the main liquid injection pipelines are connected with a liquid storage box, and each auxiliary liquid injection pipeline is connected with a liquid injection opening formed in an upper cover of the hollow box body in a clamped mode. Water or other liquid i