Three new single-atom-thick silicon-carbon stable systems have been found by using of SCED-LCAO and DFT methods. An important position, named bone position, is proposed in these structures. For SiC and Si1C9 system, the bone positions are partially occupied by Si atoms, the plane structure is kept and electronic gap is opened with 0.955 eV and 0.689 eV respectively. For Si2C8 system, the bone positions are fully occupied by Si atoms. It shows a buckled structure with a buckling of 0.05 Å and a Dirac cone at M point. Moreover, the sp hybridization between Si and C atoms in SiC system is found and the co-existence of sp, sp2 and sp3 hybridization is also found in Si2C8 system. The thermal stability for these three systems is certified.