The invention discloses a gradient filter membrane material based on nano fibers, which belongs to the technical field of a membrane material and a textile material. A nonwoven material is used as a supporting layer, and a gradient sublayer (having a gradient filter function) is coated onto the surface of the supporting layer, the gradient sublayer is a thermoplastic polymer nano fiber layer consisting of two layers or three layers of thermoplastic polymer nano fiber sublayers with different aperture structures, the sublayers are firmly combined by virtue of a chemical cross-linking effect, and a gradient layering structure is provided in the direction perpendicular to the membrane surface. Each sublayer is made of thermoplastic nano fibers of different diameter ranges, and the gradient filter membrane material requiring different filter functions can be prepared by flexibly controlling the distribution of the thermoplastic nano fibers of different diameter ranges. The gradient filtermembrane material has the characteristics great flexibility in controllability, high water flux, and high filter efficiency. Due to the unique adjustable gradient structure, the gradient filter membrane material can be widely applied to the fields of environmental water filtration and other relevant filtration.