The invention discloses a simple method for preparing a nano-silver antibacterial solution, which is mainly characterized in that the nano-silver solution is prepared by taking a high-pressure sterilizing pot as a reaction environment, utilizing silver nitrate as a silver source and using soluble starch and other polysaccharide substances as protective agents; the average particle size of the nano-silver in the solution is less than 10 nanometers; the solution can have antibacterial effects under low concentration; and the method is simple in process, high in efficiency, high in the concentration (up to 10000 ppm) of the prepared nano-silver solution, few in impurities and high in stability, and can be widely applied to electronic, textile, medical health, food, coating, plastic and other fields.