A series of CuW60Cr15 composites with different Cr particle size ranging from 43μm to147μm in diameter have been prepared by infiltration. The results show that the size of Cr particles plays an important role on the microstructures and the properties of the CuW60Cr15 composite. Fine Cr particle changes not only the size of the isolated CrCu alloy zone but also the structure of the skeletons of the composite obviously. Fine Cr particles increase not only the maximum and the minimum but also the mean value of breakdown voltage. Although the maximum value of chopping currents remains almost constant while Cr particles become finer, the minimum and the mean values of chopping current discernible decrease in the CuW60Cr15 composites. It can be seen from the SEM photos of the composites after arcing that the size and its location of the arc spot determines the chopping current value of the composites.