The invention discloses a cyanide-free electroplating nanogold electrolyte, a preparation method and a method for preparing nanogold plating from the electrolyte, relates to an electrolyte, a preparation method and an application, and aims to solve the problems of poor stability of existing cyanide-free electroplating technologies and thick gold grains obtained through deposition by using hydantoin and derivatives of the hydantoin as coordination agents. The cyanide-free electroplating nanogold electrolyte is prepared from main salt, a coordination agent, conducting salt, an additive and distilled water. The method includes the following steps that I, the coordination agent and the conducting salt are dissolved in the distilled water; II, the main salt is dissolved in the distilled water;III, mixing is performed, the additive is added, and the constant volume effect is realized. According to the method for preparing the nanogold plating from the cyanide-free electroplating nanogold electrolyte, a pure gold piece is used as the positive pole, copper foil with the surface plated with a bright nickel layer is used as the negative pole, the positive pole and the negative pole are immersed in the electrolyte used for preparing the cyanide-free electroplating nanogold plating, the temperature, the stirring speed and the current density are controlled, and electroplating is performed. The invention is applicable to preparation of the nanogold plating.