The utility model discloses a photocatalysis air purifying device based on a dispersion optical fiber, which comprises a filtering unit and a photocatalysis unit, wherein the filtering unit is a cylindrical filtering unit, the radial cross section is of an annular shape, and the upper and lower ends are connected with a top end cover and a bottom end cover respectively; an air outlet is formed at the center of the top end cover; top end mounting holes are uniformly formed around the air outlet; bottom end mounting holes are uniformly formed in the bottom end cover; the photocatalysis unit is a fibrous catalysis unit; one end of the photocatalysis unit is fixedly connected with the top end mounting holes, and the other end is fixedly connected with the bottom end mounting holes. The technical scheme of the utility model adopts a 360-degree side air inlet mode, and the influence of secondary pollution caused by the byproduct of a photocatalysis reaction can be effectively reduced; the surfaces of the HEPA and active carbon fiber are loaded with titanium dioxide at the same time, thus the utilization rate of ultraviolet light is improved, and the air purifying efficiency is effectively improved; the device disclosed by the utility model is suitable for the closed and combustible and explosive environments such as aircrafts, subways, trains and factories.