The invention discloses a silk nanofiber membrane, a preparation method therefor, and an application of the silk nanofiber membrane in a supercapacitor. The method comprises the pre-treatment, supersonic, centrifugation and filtering steps through a deep eutectic solvent, and achieves the preparation of the silk nanofiber membrane. The contact angle of the prepared silk nanofiber supercapacitor membrane and electrolyte is 20-60 degrees, and the prepared silk nanofiber supercapacitor membrane does not shrink under the temperature of 150 DEG C. The tensile strength of the prepared silk nanofibersupercapacitor membrane is 30-80 MPa. The silk nanofiber membrane provided by the invention is good in electrolyte affinity, is excellent in thermal stability and mechanical performance, greatly improves the rate capability of the supercapacitor, greatly prolongs the service life of the supercapacitor, and greatly improves the safety performance. Meanwhile, the method provided by the invention isgreen and environment-friendly, is low in cost, is simple and easy in operation, and is easy for large-scale production.