After a certain type of aircraft engine high-pressure turbine blade tip was worn,laser cladding technology was used for repair.Through X-ray inspection,longitudinal micro cracks were found on the interface between the cladding layer and the substrate,with an unqualified rate of about 20%.By analyzing the composition of the matrix material,observing metallography,scanning electron microscopy,industrial CT and other methods,the causes of cracks were analyzed.The results showed that cracks were thermal cracks caused by excessive stress during laser cladding.Increasing preheating and adjusting the laser output mode can effectively reduce the failure rate of cracks.After the implementation of control measures,we continued to track and inspect the laser cladding repair of 24 blades,with a qualification rate of over 99%.