Abstract: By means of the mercurial barometer and pore size analyzer, the effects of bridged particles on the pore volume distribution in nano-meter cemented carbide powder and its compact were investigated. Also the apparent density, specific surface area and green density were studied before and after sedimentation separating and high energy shear milling by BET specific surface area analyzer and SEM. The results show that there is more than one peak on pore volume distribution pattern because of the presence of bridged particles. The apparent density and green density can be greatly improved by high-energy milling.