Abstract: The physical properties of ultrahigh molecular weight of polyethylene (UMWPE) obtained from highly active polymerization of ethylene have heen studied-with various instrumental methods.The morphology of initial polymer was observed by scanning electron microscope.The transmitting electron micrograph shows morphology of supermolecular fibrillar fringe of polymer.The melting and cooling crystallization processes of initial (nascent) polyethylene powder of various molecular weight were studied by the aid of polarimetric microscope with the result that the spherulite size increases with molecular weight.The crystallinity of initial polyethylene powder or its annealed heat molded specimen increases with increasing molecular weight (by X-ray diffraction,DTA,inverse gas chromatographic and density determination),while the crystallite size decreases with it.The crystalling melting temperature T_m(determined by DTA and inverse gas chromatographic method) of UMWPE initial powder is about 8-12℃ higher than that of PEwith ordinary molecr.lar weight (M_W≌10×10⁴).The thermomechenical curves show that above T_mthe UMWPE molded specimens present a nonflowing rubery elastic state untill the higher viscoflowing temperature is reached.The oxidation degradation behavior has been investigated with DTAand TGmethods.Besides,the extinguished impact strength and anti-abrassion properties of UMWPEspecimens have been determined.The scanning electron micrographs for the textures of the cross-section cleavage surfaces of impacted molded specimen of polyethylene with M_W=10×10⁴and M_W=126×10⁴were interpreted from the viewpoint of molecular chain aggregation.