Two monoxides of typical smaller chlorofullerenes, (C50Cl10O)-C-#271 and (C56Cl10O)-C-#913, featured with double-fused-pentagons, were synthesized to demonstrate further regioselective functionalization of non-IPR (IPR = isolated pentagon rule) chlorofullerenes. Both non-IPR chlorofullerene oxides exhibit an epoxy structure at the ortho-site of fused pentagons. In terms of the geometrical analysis and theoretical calculations, the principles for regioselective epoxy oxidation of non-IPR chlorofullerenes are revealed to follow both fused-pentagon ortho-site and olefinic bond rules, which are valuable for prediction of oxidation of non-IPR chlorofullerenes.