Quasiparticle band structures of 3C-SiC and 2H-SiC were calculated using ab initio many body perturbation theory with GW approximation. Quasiparticle energies along high symmetry lines in the first Brillouin zone were evaluated using quasiparitcle self-consistent GW (QPscGW) method and the Maximally-localized Wannier Function interpolation. Both 3C-SiC and 2H-SiC have an indirect band gap with valence band maximum locating at point. The conduction band maximum of 3C-SiC is at X point. As a comparison, band gaps of 3C-SiC calculated by DFT-LDA, one-shot G0W0 and QPscGW are 1.30 eV, 2.23 eV and 2.88 eV respectively. The conduction band minimum of 2H-SiC locates at K point with a band gap of 2.12 eV, 3.12 eV and 3.75 eV predicted by DFT-LDA, one-shot G0W0 and QPscGW respectively. Lattice parameters calculated by DFT-LDA were used in this work. The QPscGW calculations are based on pseudopotential method, predicting slightly larger bandgaps for both 3C-SiC and 2H-SiC comparing with experiments.