Abstract: The structure of silane grafted High Density Polyethylene (HDPE) was characterized by FT-IR and Laser Raman spectroscopy.The characteristic peaks of silane at 1 170,1 110,1 090 and 960 cm^-1 were rather stronger in the FT-IR spectrum,while the characteristic peak of silane at near 1 091 cm^-1 was quite weaker in the Raman spectrum.With the increase of the silane content,the ratio of peaks (R₁) calculated from FT-IR and R₂ calculated from Raman increased respectively from 0.43 to 1.44 and from 0.028 to 0.099.Both R₁ and R₂ could be used to estimate the grafting ratio of silane and have the same concentration depen-dence trend.The crystallization of silane grafted HDPE was also characterized by Raman spectroscopy.With the increase of the silane content,Raman data showed that the mass fractions of the crystalline phase and the amorphous decreased respectively from 69.8% to 67.5% and from 12.9% to 5.5%,while the mesophase increased from 17.3% to 27%.DSC data showed that the crystallinity of silane grafted polyethylene and the melting point decreased respectively from 71.8% to 61.1% and from 134.4℃ to 131.1℃.