In order to study the effect of Ti on microstructure and properties of Co-based alloy coating,Co-based alloy and Ti/Co-based alloy composite coatings are obtained on low carbon steel surface by 5 kW CO2 laser. Microstructure,microhardness,and sliding wear resistance of the coatings are studied. The results show that Co-based alloy coating consists of γ-Co,ε-Co,Cr23C6 and Ti/Co-based alloy composite coating consists of γ-Co,ε-Co,Cr23C6,TiC and so on. The Co-based alloy coating is made up of flourishing γ-Co dendrite and eutectic structure. Equiaxed solid solution and fine eutectic structure are observed in the Ti/Co-based alloy composite coating. The influence of in-situ synthesis TiC particles on microstructure of coating is prominent. And the microstructure is refined by changing it from dendrited to equiaxed grain by TiC.