The invention discloses a preparation method of nylon salts. The preparation method comprises the steps that a dibasic acid-alkali compound is prepared and prepared into a dibasic acid-alkali solution; a diamine salt compound is prepared and prepared into a diamine salt solution; the obtained dibasic acid-alkali solution and the obtained diamine salt solution are mixed and stirred at normal temperature, and the nylon salts are separated out. According to the preparation method, the long-chain semi-aromatic nylon salt and aromatic nylon salt can be quickly and effectively prepared, heating is not needed during salt forming, a reaction endpoint does not need to be judged by monitoring the pH value on line, no organic solvent is needed, water serves as a reaction medium, and the economic property and environmental friendliness are achieved.