Based on density function theory with the ultrasoft pseudopotential scheme in the frame of the local density approximation and the generalized gradient approximation, the structural, elastic, and electronic properties of carbon with P2221 phase have been systematically studied in this paper. The calculated results show that the P2221 phase of carbon is mechanically stable and dynamically stable at ambient pressure. The anisotropy studies of Young's modulus, Poisson's ratio, shear anisotropic factor, the percentage of elastic anisotropy for bulk modulus, the percentage of elastic anisotropy for shear modulus and the universal anisotropic index show that P2221 phase of carbon exhibits anisotropy. In addition, P2221 phase is an indirect semiconductor with bandgap of 3.423 eV. But, the band gap of P2221 phase for carbon increase with increasing pressure.