The invention relates to a regular-hexagon honeycomb grid floor structure which comprises steel open-web girders. The regular-hexagon honeycomb grid floor structure is characterized in that the steel open-web girders are connected with one another to form honeycomb planar steel grids which comprise a plurality of regular-hexagon grids; regular-hexagon prefabricated plates are shelved and welded on the planar steel grids and are reinforced concrete prefabricated plates with ribbed triangular grids, the shapes of the regular-hexagon prefabricated plates are matched with those of the regular-hexagon grids and rhombic grids, and concrete layers are arranged on the regular-hexagon prefabricated plates by means of pouring. The regular-hexagon honeycomb grid floor structure has the advantages that indoor grid shapes of diversified multi-layer large-span public buildings can be enriched, and novel 'safe, reasonable, advanced and economic' structural systems can be formed.