Polyvinyl chloride (PVC) was heat-treated in a vacuum at 270℃ to prepare a partly conjugated derivative (CDPVC) through a reaction of remove HCl. The nano TiO2/CDPVC composite was prepared by compounding commercial TiO2 and CDPVC with the mass ratio of 2:1 in a high-energy ball-miller, and was characterized by TEM, XRD, XPS, FTIR, SEM and Raman, et al. The photocatalytic degradation of rhodamine B (Rh B) and the photocatalytic reduction of K2Cr2O7 were used to evaluate the visible photocatalytic activity and stability of the nano TiO2/CDPVC composite. The results show that the structure of Ti-O-C formed by compounding TiO2 and CDPVC in a high-energy ball-miller, which is advantageous to the improvement in both visible-light absorption capacity of the nano TiO2/CDPVC composite and separation efficiency of photogenerated electron/hole pairs. Compared to nano TiO2 and TiO2-CDPVC (an ordinary product after grinding TiO2 and CDPVC), nano TiO2/CDPVC composite exhibits the higher visible-light photocatalytic activity and excellent stability. The visible-light photocatalytic mechanism can be proposed that CDPVC adsorbs photos to produce photogenerated electron-hole pairs, and the photogenerated electrons can be easily injected into the conduction band of TiO2. The photogenerated electrons (eCB-) in CDPVC and conduction band of TiO2 can be captured by oxygen on the surface of the TiO2/CDPVC composite to form •O2_ radicals, and •O2_ radicals can directly degrade rhodamine B molecules even to produce H2O and CO2. © 2019, Editorial Office of Acta Materiae Compositae Sinica. All right reserved.