We suggest that the nanophase ferric oxide material provides an important niche for the early photosynthetic microorganism on the earth, which eventually leads to the oxidation of the earth's atmosphere and the formation of iron oxide deposits.

　　Today, oxygen and ozone in the atmosphere weaken ultraviolet radiation on the earth and provide substantial protection for photosynthetic organisms. Because the ultraviolet radiation flux at the early stage of earth may be higher than that of today, exposure to solar radiation is especially dangerous for early organisms. However, we know that photosynthesis then appears and play a key role in the subsequent evolution. The most important is protection at about 250-290nm, where peak nucleic acids (about 260nm) and protein (about 280nm) are absorbed. The nanophase iron oxide / hydroxyl oxide minerals absorb and prevent lethal ultraviolet radiation, while photosynthesis (400 to 1100nm) is carried out through most of the visible and near infrared regions.

　　In addition, they are available in early environments and are biosynthetic. Based on the possible geological processes of iron oxide / hydroxyl oxide spectrum and the results of photosynthetic organisms experiments. We propose a scenario for photosynthesis, and ultimately the atmospheric oxygenation depends on the protection of early microbial nano-phase ferric oxide / hydroxyl oxide. The results of this study can also be applied to other potentially habitable iron containing stars, because the evolutionary pressure of solar radiation is available when energy is available.