A　novel　strategy　to　prepare　W-Cu　nanocomposite　powder　with　WC　nanoparticles　for　strengthening　was　proposed.　The　feasibility　and　mechanisms　of　the　present　in-situ　reactions　method　for　synthesizing　multicomponent　powders　were　demonstrated　by　both　thermodynamic　calculations　and　experiments.　The　W-Cu-WC　nanopowder　can　be　prepared　at　a　low　temperature　with　pure　phase　constitution　and　homogeneous　microstructure　with　a　mean　particle　size　of　60　nm.　Owing　to　in-situ　reactions,　the　orientation　relationship　of　WC　and　W　is　formed,　which　facilitates　strong　bonding　between　the　strengthening　particles　and　matrix.　The　new　method　is　applicable　to　synthesize　a　variety　of　composite　powders　with　tailorable　phase　and　particle　size.