Tetrasulfophthalocyaninatozinc/titanium dioxide (ZnTsPc/TiO2) was synthesized by a novel in-situ and self-assembly process. The prepared products, including pure TiO2 and ZnTsPc, were characterized by XRD, UV-Vis, FTIR, Zeta potential and fluorescence spectroscopic techniques. The results indicated that ZnTsPc was indeed synthesized during the in-situ method and sol-gel process. A chemical bond (--SO2--O--Ti--) was also formed between the sensitizer (ZnTsPc) and the surface of titanium dioxide particles. The photocatalyst of ZnTsPc/TiO2 reveals greatly enhanced activity for the degradation of organic pollutant, Rhodamine B, under visible-light irradiation as compared with pure TiO2 and P25. The sensitization mechanism is that photo-generated charge carriers are separated by the chemical bond between ZnTsPc and TiO2.