Multi-walled carbon nanotube (MWCNT)-TiO2 hybrid was prepared with hydrothermal method and characterized with X-ray diffraction,electron microscopy,N2-adsorption analysis,Raman spectroscopy and Fourier transform infrared spectroscopy.The photocatalytic activity of MWCNT-TiO2 hybrid under different light resources and the effects of the tube length were studied by photocatalytically degradating RhB.The results showed that the MWCNTs were evenly coated with TiO2 nanoparticles.There was an intimate contact between the MWCNTs and TiO2.The introduction of the MWCNTs provided MWCNTs-TiO2 hybrid with visible light-induced photoactivity and a large surface area.The lifetime of photogenerated electron/hole which can enhance the photocatalytic activity was prolonged.MWCNTs-TiO2 hybrid with long length MW had higher degradation efficiency under UV lights irradiation than that with short length MW.MWCNTs (SM4) -TiO2 with a short length CNTs had the best photocatalytic activity under visible lights irradiation due to the different mechanisms of photocatalysis.