Nano-sized WC particles in WC/Co composite powders were synthesized by mechanochemical method. The raw powders and graphite) were mixed by planetary milling for 30 hours. The compositions were WC-10 and -20 wt% Co added VC and . The direct reduction and carburization of the mixed powders were carried at for 1 to 3 hours under flowing Ar gas. The mean size of WC particles in WC/Co composite powders was about 16 nm. The resultant powders were compacted and sintered at for 0.5 hour. After sintering the mean size of WC particles was about 50 nm.