Titanium dioxide (TiO2) photocatalysts, characterized by exceptional photocatalytic activity, high photoelectric conversion efficiency, and economic viability, have found widespread application in recent years for azo dye degradation. However, inherent constraints, such as the material’s limited visible light absorption stemming from its bandgap and the swift recombination of charge carriers, have impeded its broader application potential. Encouragingly, these barriers can be mitigated through the modification of TiO2. In this review, the common synthesis methods of TiO2 are reviewed, and the research progress of TiO2 modification technology at home and abroad is discussed in detail, including precious metal deposition, transition metal doping, rare earth metal doping, composite semiconductors, and composite polymers. These modification techniques effectively enhance the absorption capacity of TiO2 in the visible region and reduce the recombination rate of carriers and electrons, thus significantly improving its photocatalytic performance. Finally, this paper looks forward to the future development direction of TiO2 photocatalytic materials, including the exploration of new modified materials, in-depth mechanism research, and performance optimization in practical applications, to provide useful references for further research and application of TiO2 photocatalytic materials.