A sol-gel process catalyzed by oxalic acid is adopted to prepare SiC precursors from the raw materials of tetrathoxysilane(TEOS) and phenolic resin, and this precursors is homogeneous without the impurity of sulfur and chlorine. Sintered with a certain heating program, the obtained precursor is converted into SiC. The effect of the temperature on the hydrolyze and the influences of the amount of water, catalyzer, Nickel nitrate on the gel time are studied.The result shows that the sol-gel process is best at 40℃ and exactly after 24 hr. While the ratio of H₂O:TEOS(mol) is 0.28 and oxalic acid:TEOS(mol) is 0.01, the gel time is shortest. The further study indicates that β-SiC is converted when the catalyzer of the nickel nitrate is mixed in.