A systematic investigation of the formation of silica-coated magnetite particles via sol–gel approach was conducted using transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results show that reaction parameters including the type of alcohol, the volume ratio of alcohol to water, the amount of catalyst and the amount of precursor play important roles on the formation of silica-coated magnetite particles, and the obtained silica-coated magnetite nanoparticles possess superparamagnetic property.