A 2 kW CO 2 laser has been used to deposit single tracks of Ni based WC alloy onto a steel A3 substrate. Effects of laser processing conditions and weight fractions of WC particles on the cracking tendency of coatings are studied. Results show that WC particles are the weak points of cracking in the laser cladding composite coatings, but when WC proposition is higher, the cracking numbers in composite coatings will decrease. Effects of laser traveling speed on the cracking tendency of coatings will be altered at various WC weight fractions.