The effects of preparative parameters such as substrate temperature, ion beam voltage, ion beam current and oxygen flow on the refractive index and stress of a SiO2 thin film were systematically studied by using the orthogonal experiment design method. The transmittance spectrum of SiO2 thin film was measured by spectrophotometers, and its reflective ellipsometric characteristics were measured by an elliptical polarization instrument. Then, the refractive index and stress of the thin film were obtained by the multiple wavelength curve-fitting method and the elastic deformation of a thin film-substrate system, respectively. The experimental results show that the refractive indexes of SiO2 thin film affected by preparative parameters with the weights from high to low are in a sequence of oxygen flow, substrate temperature, ion beam current and ion beam voltage and the confidence probability of effects of the first three refractive indexes is 87.03%, 71.98% and 69.53%, respectively. Moreover, the stresses of SiO2 thin film affected by preparative parameters with the weights from high to low are in a sequence of substrate temperature, ion beam current, ion beam voltage and oxygen flow and the confidence probability of effects of the first three stresses is 95.62%, 48.49% and 37.88%, respectively. It suggests that higher oxygen flows, lower substrate temperatures and lower ion beam voltages should be selected for preparing SiO2 thin films with low refractive indexes and lower substrate temperatures, and higher oxygen flows for preparing SiO2 thin films with low stresses.