The invention relates to a dual-core organic luminescent material and a preparation method of the luminescent material and discloses a blue light organic luminescent material and a preparation of the luminescent material. According to the invention, the problems of low brightness and luminous efficiency of the blue light organic luminescent material in the prior art are solved. The molecular formula of the product disclosed by the invention is C20H24CdN6O5S. The preparation method of the blue light organic luminescent material disclosed by the invention comprises the following steps of: 1) preparation of 4-[(8-hydroxyl-5-quinoline)azo] phenylsulfonic acid; and 2) preparation of a coordination polymer: respectively dissolving a ligand and cadmium chloride into a solvent and mixing, then adding organic alkali and stirring at the room temperature for 1 hour to acquire red blocked crystals. The product prepared through the method disclosed by the invention is single crystal in a complete crystal form; and through a luminous performance test, the blue light organic luminescent material prepared through the method disclosed by the invention shows blue fluorescence and has high heat stability and favorable film forming characteristic. The yield of the product prepared through the method disclosed by the invention is higher than 40%.