In order to improve the corrosion resistance of 20 steel plate，based on the principle of photosensitive micromachining，a hydrophobic TiO₂-SiO₂ dot matrix coating filmwas prepared on the surface of 20 steel plate by the sol-gel method. The photosensitive mechanism of TiO₂-SiO₂ composite sol was emphatically studied，and the corrosion resistance of 20 steel plates protected by TiO₂ dot matrix coating，TiO₂-SiO₂ dot matrix coating and flat bottom layer/TiO₂-SiO₂ dot matrix coating was compared. The results showed that the TiO₂-SiO₂ sol indicated excellent photosensitivity to the ultraviolet light with the photosensitivewavelength of 330-380 nm，and the solubility of sensitized Ti4+metal chelates in organic solvents decreased sharply. Based on this principle，using the photosensitive sol-gel technology could obtain the TiO₂-SiO₂ lattice gel pattern with complete structure. The latticepattern made the material change from hydrophilicity to hydrophobicity，and the corrosion resistance was greatly improved，Among them，the flat bottom layer/TiO₂-SiO₂ lattice coatingfilm showed no corrosion marks on the surface after salt spray test，and this coating indicated strong protective ability for 20 steel plates.