The laser forming repaired (LFR) and GH4169 superalloy powder were used to prepare laser-formed repair parts on GH738 superalloy substrate specimens, which were subjected to solution + double aging heat treatment. The specimens were subjected to high-temperature endurance and high-temperature low circumference fatigue performance tests, the fracture morphology of the specimens was observed and the fracture mechanism was analyzed. When the persistent test was conducted at 650 ℃ and 690 MPa, the Laves phase was precipitated at the grain boundaries of the repaired specimens, leading to the crack sprouting. This will be separated from the grain boundary to form microscopic cavities, while the gas porosities promote the crack expansion, as a mixed ductile fracture mode of penetration and along with the crystal. Low cycle fatigue test at 455 ℃, the fatigue cracks originated from the surface and gas porosities and spread to the center in a river-like pattern, and there were fatigue glow lines in the expansion area, which were two fracture modes of transgranular and cleavage fracture. The GH4169 superalloy powder repair can meet the conventional casting and forging of GH738 alloy.