The invention discloses a compound PTFE / PAN (polytetrafluoroethylene / polyacrylonitrile) hydrophilic and oleophobic film and a preparation method thereof, belonging to the technical fields of film material preparation and modification. A casting film solution is prepared from the following substances in percentage by mass: 10 to 15 percent of high-molecular polymer, 10 to 25 percent of inorganic nano particle, 0 to 20 percent of additive and 70 to 90 percent of solvent. The thickness of the PTFE / PAN-SiNPs hydrophobic / oleophobic complex film is 0.4 to 0.6mm, the porosity is 30 to 50 percent, thepore size of the film is 0.1 to 1mu m, the water contact angle is less than 40 degrees, and the underwater oil contact angle is greater than 150 degrees. After alkaline leaching and modifying, the film thickness is 0.2 to 0.4mm, the porosity is 20 to 50 percent, the pore size of the film is 0.1 to 1mu m, the water contact angle is less than 20 degrees, and the underwater oil contact angle is greater than 160 degrees. According to the compound PTFE / PAN hydrophilic and oleophobic film and the preparation method thereof, the film forming technology is simple, the operation is convenient, and theindustrial production can be easily realized; the complex film has good antipollution performance, high chemical stability, good mechanical property, high interception efficiency and wide applicationprospect.