A series of Si-modified ZrO2 supports were prepared by incorporating different content of silicon and loaded 25 wt.% MoO3 for sulfur-resistant CO methanation reaction. The prepared catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), N-2 physisorption measurements, infrared spectra of adsorbed pyridine (Py-IR) and hydrogen temperature-programmed reduction (H-2-TPR). The results demonstrated that Si-modified ZrO2 achieved more stable ZrO2 phase, more oxygen vacancies, larger specific surface area and more Bronsted acid sites. Catalysts prepared by modified ZrO2 exhibited smaller metal particles and different interaction between metal and support, which possessed higher activity with 63.4% CO conversion and 59% CH4 selectivity than unmodified catalyst at 550 degrees C under 2.5 MPa with 100 ppm H2S.