Gas film sampling device of ion mobility spectrometry

The utility model discloses a gas film sampling device of an ion mobility spectrometry. The gas film sampling device comprises an ionization source, a film external cavity, a film internal cavity, a semi-permeable film, a repulsion pole, an ion neutralization disk, a sucking pump and a three-way valve. The utility model adopts the technical scheme that a negative pressure forming device is arranged in the film internal cavity; the ionization source is arranged in the film external cavity; electric fields are formed on two sides of a film; and a sample can permeate through the semi-permeable film in an ion form. Under the action of concentration difference, pressure difference and the electric fields, the sample permeates through the semi-permeable film in molecule and ion forms, and the permeation rate and permeation speed of the sample in the film sampling device are improved.