The invention provides a method for preparing a chitosan-based silver-loaded composite antimicrobial superfine fiber membrane. The method is characterized by particularly comprising the following steps: 1, adding silver nitrate powder into an acetic acid aqueous solution with the mass fraction of 50-90%, stirring to dissolve to obtain a solution, weighing and adding chitosan and polyoxyethylene or polyvinyl alcohol powder into the solution, and stirring to obtain a spinning solution; and 2, adding the spinning solution into an electrostatic spinning device, carrying out electrostatic spinning under the conditions that the voltage is 10-20kv, the spinning solution injecting speed is 0.1-1.0mL/h, the receive distance is 8-30cm, the spinning temperature is 20-50 DEG C and the relative humidity is 10-55%, carrying out vacuum drying on the obtained white nanofiber membrane for 12-36 hours, and removing the residual solvent to obtain the chitosan-based silver-loaded composite antimicrobial superfine fiber membrane. The electrospun fiber membrane has the advantages of a certain mechanical property, good antimicrobial property and water absorbing ability and can be used for the fields of wound surface nursing and medical dressings with different anti-infection requirements through designing the compositing ratio of the chitosan and the nanometer silver.