A stereo block poly(1-butene) was synthesized with η5-pentamethylcyclopentadienyltribenzyl-oxidetitanium(Cp*Ti(OBz)3) and modified methylaluminoxane(MAO) as catalyst.The original polymer was extracted successively by boiling ether and heptane, and each fraction was characterized by 13C-NMR, WAXD and DSC. It was found that ether soluble fraction was atactic poly(1 butene), heptane solube fraction was stereo block poly(1-butene), and heptane insoluble fraction was isotactic one. The isotacticity,glass transition temperature and crystallinity of the polymers soluble in boiling heptane were increased with decreasing polymerization temperature.At lower polymerization temperature (30℃ and 0℃),the polymers with the degree of crystallinity over 30% had two melting peake which were 43℃/55℃ and 85℃/88℃,respectively.But at higher temperature (40℃) noncrystalline polymer obtained from heptane-solube fraction was characterized by WAXD and DSC.The relationship between the propagation mechanism and the microstructure of the prepared products was studied by 13C-NMR. It was indicated that the 1,2-insertion was easier than 2,1-insertion.