The paper discussed the changes of crystal structure and mechanical properties of hot drawn and twice drawn sheets of UHMW-PE in melted state．The crvstal orientation of the drawn sheets were tested by using WAXD，the 200 and 020 pole figers were made and the orientation factors fa，fb and，fc were calcu-lated．The crystallite and amorphous region size along draw direction were obtain-ded by measuring the integral breadth of the 002 reflection profile and long period for the drawn sheets．The DSC curves for twice drawn UHMW-PE sheets showed that besides a main peak，a small melt peak was observed at 152--153℃．The dy-namic mechanical behavious for the hot drawn sheets and twice drawn sheets indica-ted that β-relaxation appears in lower draw ratio sheets and in higher draw ratio and twice drawn sheets β-relaxation degenerated greatly or disappeared．The Young’s modulus of twice drawn UHMW-PE were much higher than the first drawn one．The results showed that twice drawn UHMW-PE sheets had bi-component crystlliza-tion：most crystals were folded chain type，a few were extended chain crystals．Structures and properties of twice drawn sheets were improvement of first drawn one．