This paper presents the research on coaxial powder feeding laser cladding of superalloy K403 with a commercial manual-mixed nickel based alloy and a manual-mixed nickel alloy free of boron and silicon. The effects of the substrate microstructure, clad materials and cladding parameters on the tendency to cracking were investigated. The feasibility on the strengthening and repairing of superalloy turbine blades by laser cladding was discussed. The results revealed that laser cladding of nickel based superalloy free of boron and silicon is good for eliminating cracks.