Abstract: We discussed the decrease in residual stress, precipitation evolution, and mechanical properties of GH4151 alloy in different annealing temperatures, which were studied by the scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), and electron backscatter diffraction (EBSD). The findings reveal that annealing processing has a significant impact on diminishing residual stresses. As the annealing temperature rose from 950 to 1150°C, the majority of the residual stresses were relieved from 60.1 MPa down to 10.9 MPa. Moreover, the stress relaxation mechanism transitioned from being mainly controlled by dislocation slip to a combination of dislocation slip and grain boundary migration. Meanwhile, the annealing treatment promotes the decomposition of the Laves, accompanied by the precipitation of μ-(Mo₆Co₇) starting at 950°C and reaching a maximum value at 1050°C. The tensile strength and plasticity of the annealing alloy at 1150°C reached the maximum (1394 MPa, 56.1%) which was 131%, 200% fold than those of the as-cast alloy (1060 MPa, 26.6%), but the oxidation process in the alloy was accelerated at 1150°C. The enhancement in durability and flexibility is primarily due to the dissolution of the brittle phase, along with the shape and dispersal of the γ′ phase.