The reactive process of silicon carbide in Al2(SO4)3-Na2SO4 molten salts system was studied. The surface morphology and phase transition were studied by X-ray diffraction(XRD), infrared spectroscopy(IR), transmission electron microscope(TEM), scanning electronic microscope(SEM), and energy dispersive spectrometer(EDS), respectively. XRD and IR results show that silicon carbide could be completely transform into mullite whiskers. TEM result showed that the mullite crystals grew along ［111］ crystal plane firstly and developed into fibrous microstructure. An oxidation-dissolution mechanism was proposed for the explanation of the reaction of SiC powders in mixture molten salts.
