As efficient electrocatalysts for hydrogen evolution reaction (HER), novel MoS2/carbon-doped molybdenum dioxide (MoS2/C-doped MoO2) nanobelts have been successfully synthesized via sulfuration treatment of the C-doped MoO2 nanobelts. Mo3O10(C6H8N)2•2H2O with one-dimensional structure, high conductivity and large surface area has been used as template to produce C-doped MoO2 nanobelts. After the sulfuration treatment, MoS2 nanosheets vertically grow along the axis direction of conducting C-doped MoO2 nanobelts leading to less stacking of MoS2 nanosheets and improved conductivity. The as-prepared MoS2/C-doped MoO2 nanobelts have been examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). The growth mechanism of MoS2/C-doped MoO2 nanobelts has been discussed. The MoS2/C-doped MoO2 nanobelts exhibit excellent HER activity with the low onset overpotential of 120mV (vs. RHE) and a small Tafel slope of 55mVdec−1. The sulfuration treatment of C-doped MoO2 nanobelts could improve the conductivity and decrease the stacking of MoS2 nanosheets, which could provide more exposed active sites and faster rate of electron transfer, thus their electrocatalytic performances for HER have been enhanced drastically. The sulfuration treatment of unique MoOx-based nanostructures may be a potential and efficient strategy to manufacture efficient MoS2-based electrocatalysts for HER.