Non-oxide ceramic SiCN possesses unique physical and chemical properties, which make it a suitable material for various applications such as catalyst support, high temperature semiconducting devices, and metal or polymer matrix composites. In this work, SiCN foams with pore size of 500 and 1000 nm and high BET surface area of 184.5 and 71 m2/g were prepared using preceramic polymer, polyvinylsilazane, as a precursor and polystyrene sphere packed bed as a self-sacrificial template. The polystyrene sphere packed bed was prepared by the natural sedimentation of spheres. After the infiltration and curing of viscous preceramic polymer, the sample was pyrolyzed at 1000 °C under N2 atmosphere to produce the ceramic foams. It is a very simple synthesis because in the process of pyrolysing preceramic polymer, the polystyrene sphere template was removed simultaneously by pyrolysis with no additional etching step. SEM, N2 adsorption-desorption measurement and TGA were used to characterize the obtained samples. It was concluded from the TGA measurement that the obtained SiCN foam possessed very high thermal stability at 1000 °C under air.