The main drawbacks of anatase titanium dioxide (TiO2) nanoparticles for being used as a photocatalyst are due to the rapid charge recombination of the electron-hole pairs and the wide band gap energy, limiting its photocatalysis application. To enhance photocatalytic activity, structure modification was performed here. Heterogeneous nanostructure of Dy-doped TiO2 nanoparticles hybrid with Monoclinic TiO2 nanobelts (Dy/TNBs) was fabricated via hydrothermal method. Annealing temperature was varied to investigate its effect on phase composition and morphology of the as-prepared TiO2 catalyst. Phase composition and morphology were studied by XRD and SEM, respectively. The effect of amount of catalyst loaded on the degradation efficiency of methylene blue (MB) dye in aqueous solution under UV and fluorescence illumination was investigated. The results showed that pure monoclinic TiO2 nanobelts (TNBs) was achieved at 450 degrees C. Enhanced photocatalytic activity under both UV and fluorescence irradiation was found on Dy/TNB samples. The optimum Dy dosage providing the highest MB degradation rates under both irradiation sources was 0.1 mol%.