There is an important demand for cheap and efficient photocatalysts for dual functional applications. In the study, we report novel 1D MoO3-x/g-C3N4 composite using ethanol as a reducing agent to introduce oxygen vacancy (O-v). The presence of oxygen vacancy has been confirmed by X-ray photoelectron (XPS), electron spin resonance spectra and redox experiments. Compared with MoO3-x, g-C3N4 and fully oxidized MoO3/g-C3N4, the proposed MoO3-x/g-C3N4 composite exhibited a higher photoactivity, effectively degrading methyl orange in 100min and completely inactivating Escherichia coli in 15min under visible light-emitting diode irradiation. Trapping experiments demonstrated that holes (h(+)) and superoxide radicals ( O 2-) were the major active species involved in the photocatalytic process. The enhanced photoactivity was attributed to: (1) broadening of the light absorption range associated with the oxygen vacancy, which also served as electron mediators, facilitating the separation of electron-hole pairs, and (2) the 1D nanostructure of MoO3-x, which increased the lifetime of charge carriers. The results provide evidence of the advantages of the introduction of oxygen vacancy with a view to broadening the applications of this photocatalyst.