The 3C–SiC powder or the 3C–SiC/multilayer graphene composite powder was synthesized after 3 h carbothermal reduction reaction in flowing Ar at 1673 K using expanded graphite and Tetraethyl orthosilicate (TEOS) as raw materials and Ni(NO3)2·6H2O as catalyst precursor. Based on these findings, 3C–SiC/multilayer graphene composite ceramics were prepared using a one-step spark plasma sintering(SPS) method. The results showed that the reaction temperature could be reduced to 1673 K when adding 1 wt.% Ni. Furthermore, the thickness of the multilayer graphene generated in situ was approximately 3.5 nm with C/SiO2 molar ratio of 3.5:1. In addition, the water wettability of the 3C–SiC/multilayer graphene composite powders was significantly improved. Furthermore, the hardness of the 3C–SiC/multilayer graphene composite ceramic prepared by the addition of Ni catalyst was enhanced compared to the situation without any catalyst and there was no obvious agglomeration in the ceramic structure. The method of in situ ceramic phase dispersing graphene could solve the agglomeration and high costs of preparation and extended to develop a wide range of applications of graphene.