The invention discloses a preparation method of a highly polarizing fluorescent film. A fluorescent dichromatic dye and a polymerizable liquid crystal material, which has a highly ordered smectic B phase, are mixed to obtain a dichromatic mixture, the dichromatic mixture is placed in a 5 [mu]m anti-parallel friction liquid crystal box in the smectic B phase to be subjected to molecular ordered orientation, then the dichromatic mixture is in polymerization at a temperature of 45 DEG C to prepare the film, and a high linear polarization degree is realized. Based on the abovementioned technical scheme, the technology using molecular orientation to prepare a highly polarizing film has a wide application prospect in the fields of optics and liquid crystal display.