The invention discloses a nano fiber membrane filtering material with an antibacterial function and a preparation method thereof, belonging to the technical field of membrane separation. The preparation method disclosed by the invention comprises the following steps: uniformly coating the surface of a non-woven base material with a specific antibacterial agent and thermoplastic polymer in a spraying manner, preparing thermoplastic polymer nano fiber by using a melt blending separation method, and dispersing the fiber and the specific antibacterial agent by using a water-based solvent. The related processes disclosed by the invention are physical processes, and the processes are simple to operate, environment-friendly and non-pollution effects are achieved, and the industrialization is easy to realize. The nano fiber membrane filtering material with the antibacterial function, which is disclosed by the invention, has a uniform aperture, relatively high porosity and relatively dense fiber stacking density, and has not only an efficient antibacterial function, but also an excellent water generation effect.