Abstract: The steady and dynamic rheology behaviors of UHMWPE/Kaolin composites prepared by a polymerization-filling method were investigated with capillary and parallel plate rheometer. The composites showed an unusual rheological behavior.The material could be smoothly extruded through the capillary and the addition of Kaolin particles could decrease the apparent viscosity, dynamic viscosity, complex viscosity and the moduli of the melt. The relationship between rheological behaviors and the unique structure governed by polymerization-filling was further discussed.