Microstructure evolution of recycled nickel-base superalloy K417 after melt superheat treatment at different temperatures of 1530, 1650, 1700 and 1800 oC for 5 min were investigated using optical microscope (OM) and scanning electronic microscope (SEM). The size, distribution and morphology of carbides were studied. The effect of microstructure change after melt superheat treatment on tensile properties at room and elevated temperatures was analyzed. Results show that the propagation of cracks is prevented effectively due to the morphology changes of carbides from block to script during the melt high temperature treatment, which results in higher strength and ductility of K417 alloy at room and elevated temperatures