The unusual flow behaviors of linear PE melts are caused by high molecular weight, tight entanglements of molecular chains, and strong adsorption of the melt at the capillary wall. Especially, the extreme change of interface adsorption is followed by an unusual flow, and at the molecular level, the dynamic variety of entanglement and disentanglement between the adsorption chain near the wall and the nonadsorption chain is the cause of the extrusion pressure vibration. Ultrahigh molecular weight polyethylene (UHMWPE)/kaolin composites prepared by polymerization filling could be smoothly extruded through the capillary. Also, with increase of the kaolin content, the apparent viscosity of the composite decreased and the processability was improved. Under slip boundary conditions, the real shear rate and shear stress of the melt near the capillary wall were reduced. The viscosity descent (desorption) and the deformation energy decrease of the melt near the wall were the important preconditions to gain a steady flow in a second glossy zone.