A novel SiBCN hybrid resin was prepared from 1,7-bis(dimethylsilyl)-m-carborane and viny-containing polysilazane. Composition, curing behavior, thermal stability,thermal pyrolysis reaction and process were studied by FT-IR, DSC, TGA and PyGC-MS. The curing and pyrolysis reaction activation energy were calculated by Kissinger equation and Flynn-Wall-Ozawa(FWO) methods. The pyrolysis mechanism of cured SiBCN was also analyzed.The results showed that there is one exothermic peak during the curing reaction, and its curing reaction activation energy is 113.55 kJ/mol. SiBCN possessed an excellent thermal stability with the T_d⁵ and the residue weight of 73.1% at 900℃ in N₂.The decomposition reaction activation energy of the resin and the thermal stability increased following by the reaction conversion. When the pyrolysis temperature reached 300℃,NH₃ apperad resulting from the transamination reaction, whereas CH₄,CH₂ CH₂ and alkene produced at 500℃ and further species of the pyrolysis gas such as alkanes and alkenes occured at 650℃.