The invention discloses a method for preparing an organic phosphonic gold chloride (I) compound. The method comprises the following steps: (1) adding chloroauric acid hydrated salt into a reaction container, dissolving with water, and uniformly stirring in an ice-water bath; (2) keeping the temperature of the ice water in the reaction container, dripping a glucosinolates diaryl compound or a derivative of the glucosinolates diaryl compound, and stirring uniformly; (3) dripping a mixed liquid of phosphine-containing ligand and ethanol into the reaction container one droplet by one droplet, removing the ice-water bath, recovering the room temperature naturally, and stirring for 2-5 hours; (4) stopping stirring, performing suction filtration, washing with cold methanol, dissolving the collected solid with an organic solvent, and performing suction filtration again so as to remove insoluble matters; (5) performing concentration spinning drying on the solution, recrystallizing with a solvent, and performing suction filtration again, thereby obtaining the organic phosphonic gold chloride (I) compound. As the glucosinolates diaryl compound or the derivative of the glucosinolates diaryl compound is taken as a reduction reagent, and due to reaction between the chloroauric acid hydrated salt and the phosphine-containing ligand in an ethanol-water system, environment-friendly, safe and efficient production of the organic phosphonic gold chloride (I) compound can be achieved, and moreover, industrial application of the organic phosphonic gold chloride (I) compound is facilitated.