[en] As one of the breeding blanket candidates for China Fusion Engineering Test Reactor (CFETR), the water-cooled ceramic blanket (WCCB) was proposed to use binary mixed breeding pebble bed in order to increase the packing factor and meet tritium breeding ratio requirement. The DEM method was used to establish the packing structure of binary pebble bed which can meet the neutronics requirements and the flow characteristic of helium in the pebble bed was analyzed by CFD simulation. Porosity distribution, velocity distribution and pressure drop in the pebble bed were discussed. (authors)