CoCrMoW alloy powder for 3D printing was prepared by vacuum gas atomization. Particle characteristics was studied and the Ell.Elongation, ISO Circularity, Outgrowth were introduced to characterize the particle shape. And the Selective Laser Melting forming properties of the powders and electrochemical properties of the formed parts were studied. Results indicate that the measured D10, D50 and D90 are 12.50 μm, 28.71 μm and 58.05 μm, respectively. Majority powder particles are spherical or near spherical in shape and the mean Ell.Elongation and ISO Circularity are 0.212 and 0.607, respectively. About 74.89% of the powder particles have no adhesion on the surface. The apparent density and tap density are 4.82 g/cm3 and 5.71 g/cm3, the compressibility is 15.6 %. The CoCrMoW powder was used for Selective Laser Melting and the relative density and surface roughness are 98.7% and 8.3 μm, respectively. The microhardness, tensile strength, yield strength and elongation are 396.4 HV, 1154 MPa, 852 MPa and 8.5%, respectively. And the corrosion resistance of CoCrMoW alloy prepared by Selective Laser Melting is better than that of the cast alloy.