Abstract: Superhydrophobic polyethylene terephthalate (PET) filter was prepared by sol-gel method with PET filter as matrix material, tetraethyl orthosilicate (TEOS) and methyl triethoxysilane (MTES) as modifiers. Field emission scanning electron microscopy (FESEM-EDS), Fourier transform infrared spectrometer (FTIR) and contact angle measurement were introduced to investigate the micro morphology, surface composition and contact angle of PET filter material before and after modification. The results show that the porosity of the filter material is slightly changed after modification. TEOS-modified PET (T-PET) filter material shows superhydrophilic due to the formation of a large numbers of hydrophilic —OH groups. On the contrary, hydrophobic —CH₃ groups are existed on the surface of MTES modified PET (M-PET) filter material, which endows high hydrophobicity. Moreover, TEOS and MTES modified PET (MT-PET) filter material displays superhydrophobicity due to lots of SiO₂ nanoparticles covered by —CH₃ groups are deposited on the fiber surface, reducing the surface energy of the filter material and forming micro-nano, wrinkled and even convex structure. MT-PET presents static contact angle (WCA) of (158.8±1.2)° with water shedding angle (WSA) of (6.9±1.5)°, indicating superhydrophobic state of MT-PET filter material. In addition, through the contrast test of spraying wet dust and soaking filter material in water (room temperature), it shows that MT-PET filter material has good self-cleaning performance and stability. In conclusion, the preparation of superhydrophobic MT-PET filter material in this paper has potential value for the research and development of bag filter material in high humidity environment.