Surface modification was conducted on the basic magnesium sulfate whiskers (MSW) using sodium stearate. The modification performance was evaluated by comparing the activation index, oil absorption value, rest angle, and dispersibility in polypropylene (PP) resin prior to and after treatment. It was found that the surface properties of the whiskers were improved by sodium stearate modification. In particular, the improvement in the dispersibility in PP was significant. Surface characterization was conducted using scanning electron microscopy (SEM), thermogravimetric-differential scanning calorimetry (TG-DSC) and fourier transform infrared spectroscopy (FTIR) for the raw and modified whiskers. The results indicated the co-existence of both chemical and physical adsorptions of sodium stearate on the surfaces of MSW.