Composite particles with ultra-high molecular polyethylene (UHMWPE) core and carbon black (CB) or carbon nanotube (CNT) shell were produced by particle composite system, then molded into conductive polymer composites. Morphology of these composite particles was investigated by scanning electron microscopy (SEM). Matrix particles are coated with CB or CNTs very well. And CNTs are not being cut short. The results of electrical behavior study show that these polymer composites have low percolation threshold. Conductive networks of CB and CNT were seen by optical microscopy. Related mechanism is discussed. (C) 2008 Published by Elsevier B.V.