The invention relates to a preparation method for a sandwich type medical stone/polymer composite film. A conventional isolation-type film is prepared through a film laying machine; the prepared gaps are not nature enough; spatial gaps almost do not exist; the gaps are single; the mutual stress is non-uniform; the film is relatively thick, so that the air permeability is poor; certain isolation-type films are prepared by using a spinning technology; but in order to isolate dust better, the films with very small preparation gaps are mostly selected for isolation processing, so that the air permeability is poor, the transmittance is low, and the application field is not wide enough. The preparation method comprises the following steps: firstly, preparing polylactic acid and a medical stone spinning solution; then, enabling the polylactic acid solution and the medical stone spinning solution in a spinning needle tube to separate from a needle head under the action of a high-voltage electric field through an electrostatic spinning principle; finally, forming a polylactic acid filament and a medical stone filament between receiving screens, and forming an irregular electro spinning film. The invention discloses the preparation method for the sandwich type medical stone/polymer composite film.