The invention provides a preparation method of an activated carbon fiber photocatalysis net loaded with a nano titanium dioxide, including the following steps: (1) immerging an activated carbon fiber cloth or a activated carbon fiber felt into ammonia water solution, cleaning by ultrasonic , washing by water, then immerging the washed product into nitric acid solution, processing by ultrasonict, washing again by water, and then immerging the product in acetone and then taking out and washing by water, and drying; (2) immerging the product of step one into epoxide resin acetone solution containing nano TiO2 powder, then drying in the vacuum, roasting for 2-4 hours at a temperature of 370-570 DEG C under nitrogen atmosphere, and cooling, thus obtaining the activated carbon fiber photocatalysis net loaded with nano titanium. The invention has degradation efficiency of formaldehyde as high as 80-90%, good load intensity, high unit mass activated carbon fiber TiO2 load factor and high specific surface area, can fast degrade volatile organic contaminant and can be used repeatedly.