The superplastic forming and diffusion bonding (SPF/DB) is applied in aviation and space flight field. The SPF/DB process with gas pressure control for dissimilar superalloy structure was studied. Diffusion bonding parameters, including bonding temperature T, pressure P, time t, affect the joining mechanism. When the bonded specimen with 50&m thick nickel foil interlayer was tensile at room temperature, shear fracture of the joints with nickel foil interlayer takes place at the GH4141 superalloy part. The SPF/DB of four-layer sheets structure was investigated. The optimum parameters for the SPF/DB process are: forming temperature T=1243K, forming pressure P=1MPa, forming time t=35min. The microstructure of the bonded samples was characterized. The microstructure shows an excellent bonding at the interfaces. The distribution of thickness after SPF/DB was investigated.