Nanofibrous ultrahigh molecular weight polyethylene (UHMWPE) was synthesized via Ziegler-Natta catalyst anchoring on MCM-41 and SBA-15 as supported catalysts, respectively. These supported catalysts exhibited high activity at different temperatures and Al/Ti ratios, and showed different polymerization kinetics behaviors which were well explained by their different pore structures. The ultrahigh molecular weight of polyethylene might be due to the restrained spaces of the supported catalysts mesopores prohibiting the polymer chains transfer reaction. The obtained nanofibrous morphology might be for the high enough stress generated in the mesopores extruding the polymer out to form.