Nano silicon carbide ceramics were prepared via precursor pyrolysis. Polycarbosilane (PCS) and divinylbenzene (DVB) were selected as a precursor to silicon carbide ceramics and a cross-linking reagent for PCS, respectively. The cross-linking properties and pyrolysis of PCS and DVB were investigated by changing the mass ratios of PCS/DVB. The mass ratio of PCS/DVB has a great effect on silicon carbide ceramic yield. The cured PCS/DVB with a mass ratio of 1:0.5 has the highest SiC ceramic yield (63.1%) at the temperature up to 1500 °C and its pyrolyzates consiste of nano silicon carbide with a diameter of 10-40 nm. The microstructures of the nano silicon carbide ceramics were characterized by SEM and XRD. The pyrolysis behavior of the cured PCS/DVB was characterized by thermogravimetry in nitrogen atmosphere.