The dispersibility of photocatalysts in cement-based materials has always been one of the important factors restricting the performance of photocatalytic cement-based materials. In this paper, photocatalytic cement-based materials were in-situ synthetized by adding bismuth-based photocatalytic precursor solutions in the molding process of cement-based materials. The dispersion of photocatalysts in cement matrix was improved. The photocatalytic properties to cement-based materials were imparted and the compressive strength of cement matrix was improved. The microstructure and composition of photocatalytic cement-based materials were characterized by scanning electron microscopy and EDS energy spectroscopy. The results show that the rhodamine B degradation efficiency of photocatalytic cement-based materials reaches up to 91.64%. The degradation efficiency of nitrogen oxides reaches up to 15.03%, and the early mechanical strength increases by about 10%. The photocatalyst is more uniformly dispersed in the cement matrix, and the density of cement matrix is improved. In this paper, the photocatalytic performance and mechanical performance improvement mechanism of in-situ photocatalytic cement-based materials are revealed, which provides a theoretical basis for the preparation of other functional cement-based materials.