A colorless monoclinic crystal of dichloro-benzoxazine was obtained and examined bysingle crystal X-ray diffraction analysis. At the same time, molecular modeling analysis of ninebenzoxazine compounds with different substituting groups was performed. Both single crystalX-ray diffraction analysis and molecular modeling analysis provide a detailed picture of molecularstructure on molecular level and show good consistence with each other. On the basis of structuralanalysis, the effects of molecular structure parameters on ring-opening polymerization of ben-zoxazines have been explored.