Abstract: The study of halo phenomenon gives us a new understanding of nuclear structure, in which the continuum, especially the resonance in the continuum, plays an important role. The complex momentum representation (CMR) method can not only describe the bound state, resonant state and continuous spectrum uniformly, but also describe the narrow and wide resonance well. In this paper, the CMR method is introduced for the study of nuclear resonance. The single particle energy of bound state and resonance state of ³¹Ne and ¹⁹C with deformation parameter β₂ is given. The physical mechanism of halo formation in ¹⁹C and ³¹Ne and the reason of energy level inversion near the neutron number N=20 are analyzed. The halo phenomenon in nuclei heavier than ³⁷Mg is predicted. The result of this prediction is helpful to find heavier halo nuclei in experiments. These studies show that the CMR method is suitable for describing not only stable nuclei, but also exotic nuclei with diffuse material distribution.