The influence of catalytic polymerization temperature and time on structure and properties of the synthesized naphthalene pitch prepared by using naphthalene as raw material and HF/BF3 as catalyst was studied.The molecular structure of naphthalene pitch was investigated by elemental analysis (EA),infrared spectroscopy (FT〖CD*2〗IR),nuclear magnetic resonance spectroscopy (1H〖CD*2〗NMR) and mass spectrometry (MS) analyses.The results show that the softening point(SP.),coking value,toluene insoluble(TI) and aliphatic hydrogen especially Hβ content of naphthalene pitch increase but the aromatic hydrogen content reduces with the increases of catalytic polymerization temperature and the holding time. More content of naphthenic structures and lower methyl content were found in naphthalene pitch synthesized in higer catalytic polymerization temperature.