As a green, sustainable, and low-cost catalytic technology, photocatalysis has great application potential in effectively purifying the atmosphere at low concentrations of NOx (ppb level), ensuring air quality, regional and global climate. The inorganic semiconductor-based photocatalysts have several disadvantages, such as small adsorption capacity, low adsorption rate for low concentration NOx, and easy recombination of photogenerated electrons and holes, resulting in low photocatalytic efficiency. Therefore,this study proposed to synthesize metal-organic frameworks(MOF) material with ultra-high specific surface area and porosity as photocatalysts to remove low-concentration NOx in the atmosphere. NH2-MIL-125(Ti) crystals were synthesized by the solvothermal method with different reaction time, and the effect of preparation time on the photocatalytic performance of the catayst was explored. XRD, SEM, FTIR, PL, EPR, and BET were used to analyze the structure,morphology and photocatalytic performance of different NH2-MIL-125(Ti)crystals. The relationship between the NOx catalytic performance and the catalytic preparation time was further explored. The results showed that the preparation time has a certain influence on the crystallinity, apparent morphology, photogenerated electron-hole recombination efficiency, and surface superoxide radical production of NH2-MIL-125(Ti). But it has no effect on the surface functional group type, light absorption range, and lattice crystal plane. The purification efficiencies of NH2-MIL-125(Ti) on NOx were 38. 22%,42.24% and 32. 04%,respectiuely, corresponding to the preparation time of 24 hours,48 hours,and 72 hours. As a result, NH2-MIL-125(Ti) prepared under 48 hours showed optimal catalytic performance and purification efficiency.