A simple approach to fabricate silicon carbide (SiC) whisker is reported via using cellulose nanocrystal (CNC) as templates. The CNC with a length between 2 and 4 m and a width about 40 nm is prepared by hydrolysis of microcrystalline cellulose (MCC) in strong sulfuric acid condition. The sol-gel reaction of tetraethyl orthosilicate (TEOS) is employed to coat the CNC in the presence of acetic acid as acid catalyst. The SiC whisker is obtained by calcination of CNC/SiO2 hybrid at 1200 degrees C. The obtained SiC whisker is found to have uniform size and shape with a length of ca. 2-4 m and a width of 40 +/- 5 nm. XRD, SEM, TEM (HRTEM), SAED, EDX and FTIR are used to characterize the samples. The obtained SiC whisker is used in polystyrene (PS) resin toughened. And mechanical properties of SiC/PS composites are tested by tensile impact experiments. The test results show that the 5 wt. % SiC whisker particles can disperse homogeneously in the PS resins which use a silane coupling agent (KF9701) as compatibilizer. Our results also show that the SiC whisker is excellent reinforcing material, which the tensile strength of SiC/PS composites attains 110 MPa and the Izod notched impact strength attains 5.00 KJ/m(2). Comparing the pure PS resin, the tensile impact of SiC(5)/PS(94.5)/KF9701(0.5) composites can be increased by about 3 times and the Izod notched impact strength can be increased about 8 times. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013