Abstract: The surface of basic magnesium sulfate whiskers were modified with sodium stearate as modifier, and the modification effect was evaluated by activation index, oil adsorption value and rest angle. And the whiskers were characterized beforekind after surface modification by SEM, TG-DSC and FTIR. The results showed that modification effect is so remarkable that the activation index is up to 99.21% from 0.87%, oil adsorption value loweres to 349 mL/(100 g) from 488 mL/(100 g), and the whisker surface become hydrophobic from hydrophilic. The liquidity and dispersibility of the modified whiskers are both improved significantly and no obvious effect of the surface modification process is found on the whiskers' thermal decomposition. As a conclusion, both the chemical and physical adsorption are functioning sodium stearate and the whisker surface.