The microstructure of Co-Cr-W alloy plasma surfacing has been investigated using metallurgical phase, X-ray diffraction, SEM and TEM. The results indicated that the alloy layer was composed of Co base solid solution with the preferred direction at (200) crystal plane and (Cr, Fe)7(C, B)3. The TEM research showed that there was a lot of stacking fault ribbons lying in Co-base solid solution. The result also showed that (Cr, Fe)7(C, B)3 was hexagonal lattice with lamellar and flake twin.