Bis(4-butoxycarbonylaminocyclohexyl) methane (H12 MDU) was prepared using dicyclohexylmethane-4,4'-diisocyanate and 1-butanol as raw materials and two solid products A and B were obtained. The structures of the two solid products were characterized separately by melting point measurement, infrared spectroscopy, elemental analysis, NMR spectrum analysis and mass spectrum analysis. The results show that both A and B are the target products H12 MDU. The solid A is trans-trans-H12 MDU while the solid B is a mixture including trans-trans-Hiz MDU and at least one of cis-trans-H12MDU and cis-cis-H12 MDU.