The invention discloses a method of preparing transparent pigment yellow 180. The method comprises the following steps: preparing a diazotization solution, preparing a coupling solution, preparing a buffer solution through ammonium chloride and ammonia water, controlling the pH to 7-7.5, adding bi-octadecyl-dimethyl ammonium chloride, firstly, dripping 1 / 20-1 / 8 of the coupling solution, simultaneously dripping the diazotization solution and the coupling solution, controlling the dripping reaction time to 15 minutes to 8 hours, and controlling the reaction temperature to 10-50 DEG C; continuing to stir after dripping the solutions to ensure a complete coupling reaction, filtering and washing to remove the inorganic salt and a part of water-soluble impurities to obtain a crude product, adding an assistant and water, heating, and finally, filtering, drying and crushing to obtain a finished product. The method generates little production in the production process, the cost is low, the produced pigment is uniform in particle diameter distribution, the particles are soft, the crystal structure and crystal size are uniform with the product treated by an organic solvent, and the product is high in color strength, bright in color and excellent in light resistance and solvent resistance. The acylamino in the groups of the pigment yellow 180 greatly improves the combination firmness of the molecules, thereby improving such properties as solvent resistance, heat resistance, and the like.