Laser cladding Co-based alloy coating (Co60) and Co-based alloy composite coating with 25(mass)% Cr3C2 particles (Cr3C2/Co) on low carbon steel substrate were obtained by 5-kW CO2 continuous wave laser. Effects of Cr3C2 particles on microstructure, micro hardness and corrosion-wear resistance of Co-based alloy coating were discussed. The results showed that the good laser cladding coatings were obtained in the test conditions. The Co60 coating is consisted of many γ-Co dendritic solid solution and eutectic structure (γ-Co and (Cr,Fe)7C3) between the dendrites. The Cr3C2/Co coating is consisted of undissolved Cr3C2 particles, many different shape rich-chromium carbides (M7C3,M23C6) and very finer dendrite and eutectic structure between the carbides. Addition of Cr3C2 particles alters the solidification characteristic of the laser cladding coating Co60, transforming the hypo-eutectic crystal mode of Co60 to hyper-eutectic crystal mode of Cr3C2/Co. Cr3C2 particles play a role of non-spontaneity nucleation, and many rich-chromium carbides are formed around Cr3C2 particles, fining the dendrite structure. Micro-hardness and corrosion-wear resistance in different corrosion media of the Cr3C2/Co coatings are obviously higher than those of Co60 coatings.