The transmission spectra of one-dimensional (1D) photonic crystals (PCs) with parallel and twisted nematic liquid crystals (LCs) as defect layers are discussed by 4 × 4 matrix method, respectively. The results show that the photonic band gap (PBG) mainly depends on the periodic arrays of dielectric composites. The orientation of director and the symmetry of the director configuration have important influence on the location and amplitude of defect modes. The location and amplitude of defect modes can be controlled conveniently by changing the orientation of director. The symmetry of the director configuration can help us understand the defect modes spectra.