Low-pressure chemical vapor deposition and infiltration was used for the first time to fabricate SiBCN ceramics with proper dielectric properties to lower the preparation temperature. SiBCN ceramics indicated by thermodynamic phase diagram with different phase compositions from CH3SiCl3-NH3-BCl3-H-2 could be obtained through adjustable parameters. The as-prepared SiBCN ceramics fabricated above 900 degrees C showed proper dielectric properties with dielectric loss of about 0.1, which was due to the generation of amorphous carbon and SiC nanocrystals.