Abstract: Polyethylene with a broad molecular weight distribution was prepared using hybrid catalysts in presence of montmorillonite nanocomposites forming a composite in situ. The exfoliation of the layeyed silicates in the composites was confirmed by XRD and TEM observation.  The broad molecular weight distribution characteristic for the composites was revealed by the GPC profile (MW/Mn=7 .23)，which was mainly due to different response to hydrogen regulation for active sites generated by hybrid catalysts. The composite gave rise to an elongation at break of 900%and a tensile strength of 40 MPa.

Key words: broad molecular weight distribution polyethylene, in situ polymerization, montmorillonite, nanocomposite, mechanical property