Five iodine boracites, M3B7O13I (M = Mn, Fe, Co, Ni, Cd), have been synthesized by reactions of metal oxide, B2O3, element B, and I-2 at intermediate temperature above 350 degrees C. Powder X-ray diffraction analyses verify the identities and purity of the products, which are also confirmed by magnetic property measurement. Except safe, cheap, and convenient, this novel method is significantly flexible in the selection of the starting metal oxide. The influence of the reaction temperature and time has also been studied.