Photocatalyst for wastewater purification was prepared by using TiO2 as a photocatalyst and MWCNT as an electron transferring additive. Polymer nanocomposite was prepared by dispersing the photocatalyst in the hydrogel consisting of hydrophilic poly(vinyl alcohol) (PVA) and pH-responsive polyacrylamide (PAM). Characteristics of PVA/PAM/ TiO2/MWCNT nanocomposite were investigated by SEM, XRD, FTIR, and UV spectrometer. Electron transferring effect of MWCNT played an important role in the significant improvement of photocatalytic decomposition of organic dye by PVA/PAM/TiO2/MWCNT nanocomposite.