As extension agent of titanium dioxide, calcined kaolin is applied in such fields as water-based paint, paint, putty, and sealant. On one hand, with good light scattering, it can provide good covering property, partially replacing expensive titanium dioxide, and reduce coating cost. On the other hand, with high whiteness, high dispersibility, and stronger chemical inertness, it can adjust coating’s gloss, and improve coating system’s storage stability, pigment’s anti-floating color, and coating’s weather resistance, acid resistance, and alkali resistance. In particular, it is essential to prepare low-VOC and high solid content coating.