We have analyzed an optical system for a spin-polarized atomic hydrogen beam. By calculating the model emittance of atomic hydrogen beams, we simulated the beam profile. We predicted that a hexapole magnet with a length of 75 mm and magnetic flux density of 0.65 T results in a spin polarization of 95% and a beam separation of 9 mm, which is sufficient for our purpose. We also found that the longer hexapole manget results in a higher spin polarization and smaller beam separation.