Abstract: Hydrophobic calcium carbonate particles were prepared in situ via the carbonation route by mimicking biomineralization and modified by sodium stearate (NaSt) as a modifier. The modification effect of CaCO₃ was revealed by testing its active ratio，the value of oil absorption，whiteness and the contact angle. The products were characterized through a transmission electron microscope (TEM) and X-ray diffraction (XRD). Then the reaction mechanism was discussed preliminarily. When the dosage of modifier reaches to 2.0 %，the active ratio of CaCO₃ modified by NaSt is 99.9 %. Moreover，the contact angle is 121.62°. Thereby the theory support and synthesis methods will be offered for the preparation of biomimetic materials.