The invention discloses an organic boron complex with a fluorescent property and a preparation method of the organic boron complex. The organic boron complex has a molecular formula of C27H21N4O3B, and the crystal of the complex belongs to a monoclinic system, and has the following unit cell parameters: a=9.6544(5) , b=14.1558(8) , c=16.4314(9) , alpha=gamma=90o, and beta=97.730(5)o; one boronatom, two benzimidazole ligands and a methanol solvent molecule are contained in each asymmetric unit, and in the crystal, a one-dimensional chain structure of the entire crystal is formed due to no participation of the methanol solvent molecule in coordination and the presence of intermolecular hydrogen bonds. The invention also provides the preparation method of the organic boron complex at thesame time, the method has mild reaction conditions, a simple preparation process and low cost, and the obtained organic boron complex has strong fluorescence and good thermal stability at the same time.