Using 1,7-carborane as raw material, carborane-silanol A of which Si atom was connected to carborane cage directly and carborane-silanol B having a methylene group between Si atom and carborane cage were synthesized. Taking A and B as monomers, subjected to polycondensation at high temperature with bis(dimethylamino)dimethylsilane, polymers P1 and P2 with different backbones were prepared. The structure of products was characterized by FT-IR and ¹H-NMR. TGA and DSC were introduced to study the thermal properties of P1 and P2. The results indicate that carborane-siloxane polymers can be successfully prepared using these two carborane silanol monomers, the introduction of carborane group can effectively improve thermogravimetric properties of polymers, char yields of P1 in nitrogen and air at 700 ℃ are 81% and 98% respectively, those of P2 are 53% and 70% respectively, which are much higher than those of usual silicone polymers. After high temperature treatment, there still exist strong B-H absorption peaks in the infrared spectra of polymers, which shows that carborane group still remains.