Powder metallurgy (PM) nickel-based superalloys are widely used as high-temperature, fatigue-resistant components in aircraft and gas turbines. However, many powder particle boundaries and carbides are found in alloys prepared via traditional methods, such as hot pressing (HP) and hot isostatic pressing, causing serious damage to the properties of PM superalloys. New methods and processes must be developed to improve the performance of PM superalloys. SEM, EBSD, and TEM were used in this work to investigate the microstructure, mechanical properties, and oxidation behavior of FGH4097 alloys prepared via spark plasma sintering (SPS) and HP. Owing to the advantages of uniform microstructure, fine grain, and less carbide precipitation, SPSed alloy has better tensile properties and oxidation resistance than HPed alloy. At 25^oC, SPSed alloy's yield, tensile strengths, and elongation are 998 MPa, 1401 MPa, and 17.1%, respectively; whereas those of HPed alloy are 951 MPa, 1262 MPa, and 14.4%, respectively. Although the two alloys exhibit similar yield and tensile strengths at 700^oC, SPSed alloy shows merely 80% higher ductility than HPed alloy. The oxidation mass gain of the two alloys oxidized at 900^oC for 100 h follows the parabolic law. A continuous and dense Al₂O₃ scale is formed on the surface of SPSed alloy, which effectively prevents the inward diffusion of O and outward diffusion of Cr and Ti. The mass gain is merely 0.19 mg/cm², and the oxidation rate is 1.03 × 10^-7 mg²/(cm⁴·s). Conversely, the oxidation rate of HPed alloy is approximately 2.6 times that of SPSed alloy. Severe internal oxidation occurs in HPed alloy, resulting in abundant less protective NiCr₂O₄ and TiO₂ formation on the surface, as well as large cracks and spalling.