The photocatalytic reduction of CO2 is a green, environmental-friendly energy conversion way to realize the carbon cycle of ecosystem. This method can effectively convert greenhouse gases into renewable fuels, thus alleviating energy crisis and global warming problems. This review represented recent research work on the semiconductor composites in photocatalytic reduction of CO2 and the reaction conditions and photocatalytic mechanism of photocatalytic reduction of CO2. Based on the previous reports, the main types of semiconductor composites of photocatalytic reduction of CO2 were summarized, i.e., pure semiconductor photocatalysts, metal and nonmetal doped semiconductor photocatalysts, composite semiconductor photocatalysts, and carbon-based semiconductor photocatalysts. In addition, the advantages and disadvantages of various photocatalytic materials and some factors affecting photocatalytic activities were also analyzed. The future research aspects on the catalytic reduction of CO2 by semiconductor composites were prospected.