The invention discloses a method for synthesizing gold potassium citrate for gold plating through one step.The method includes the steps of adding chloroauric acid, malononitrile and potassium citrate to an ethylenediaminetetraacetic acid (EDTA) water solution at the same time, wherein the pH of the EDTA water solution is pre-adjusted to be 8-8.5 in advance; reacting for 4-6 hours at a reaction temperature of 50-60 DEG C, conducting cooling, recystallizing and filtering to obtain white or light yellow solid, and conducting vacuum drying on the obtained solid to synthesize gold potassium citrate.Water serves as solvent, the method is easy to control, safe, environmentally friendly, low in cost and high in yield, conforms to the green chemical concept, and more critically, solves the problems that an existing synthesis method has many steps and is complex to implement; by means of the one-pot cooking method, the cost for industrial production is further reduced.The total CN- content in synthesized gold potassium citrate is greatly decreased compared with the content of potassium gold cyanide, the gold plating effect is better, and more economic value is achieved.