Dispersing conductive carbon black (CCB) particles into silicone rubber (SR), we studied the conductivity and piezoresistivity of particles filled polymer composite. The experimental results show that the conductive percolation threshold and shape exponent of composite are effected on by filler's size and reduce with filler's size decreasing. The electrical resistance and Young's model of composite have different critical filler volume fraction to fall or increase. The compressing deformation is the main reason of the piezoresistivity of composite, but the piezoresistivity is more obvious when particles have larger size or polymer matrix has smaller Young's Model. A research was done to explain the piezoresistivity through comparing CCB/SR with CCB/high density polythene (HDP). The other interesting find is that the electrical resistance of composite decreases with time under an invariant load, showing "electrical resistance creep" behavior, which is due to the composite's compressing strain creep under uniaxial pressure. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 2035-2039, 2010