By first-principles calculations we found the magnetic ground state of LiFeAs is striped antiferromagnetically with the Fe layers antiferromagnetically coupled along the z axis in the orthorhombic Cmma structure. This Cmma structure can be obtained from a structural distortion of the striped antiferromagnetic tetragonal P4/nmm structure. The lattice dynamics calculations suggested the orthorhombic Cmma is stable. The density of states at the Fermi level is mainly from the contribution of Fe 3d orbitals. These results suggest that LiFeAs has similar magnetic, structural and electronic properties to NaFeAs at low temperature.