Polycrystalline MoO3 thin films were fabricated on silicon substrates at low temperature by plasmaenhanced atomic layer deposition (PEALD) using molybdenum hexacarbonyl and oxygen as precursors. Crystal structure, surface morphology, elemental composition of the deposited MoO3 films were characterized by XRD, SEM, AFM and XPS. Results show that the crystal structure and surface morphology of the fabricated MoO3 thin films are highly dependent on the substrate temperature and the pulse time of the oxygen plasma. When the substrate temperature is 170℃ and above, the asgrown film is αMoO3. Highly (0k0) preferorientated MoO3 thin films can be obtained at 170℃ by properly prolonging the pulse time of oxygen plasma to 60s. The films are followed by the island growth mode based on the AFM analysis.