GH4169 alloy is an important material used for aviation and aerospace engines because of its excellent mechanical properties in the temperature range from -253 ℃ to 650 ℃. In order to improve the safety and reliability of engines, it is crucial to obtain the forging with a uniform and fine microstructure. Generally, theforgings with large size and complex shape, such as turbine disks and engine shafts, are manufactured by multi-stage hot working processes. In addition, the microstructure of the alloy is sensitive to the hot deformation parameters. Therefore, the defects of coarse grain and duplex grain always appear in the forgings. As the δ phase in the alloy can control grain growth through the strong pinning effect, the Delta process (DP) has been developed, which uses an intentional δ phase precipitation cycle and subsequent thermomechanical processing to produce uniform fine grain billet and bar stock. In this work, for the DP of GH4169 alloy, the effect of δ phase on the tensile deformation behavior of GH4169 alloy at high temperature was studied by the tensile tests at 950 ℃. The result indicated that the tensile stress-strain curve of the GH4169 alloy with 8.21% pre-precipitated δ phase was the elastic-uniform plastic curve, and there were two different deformation processes during the uniform plastic deformation stage. The strain hardening exponent in the first deformation process was 0.494, which was higher than 0.101 in the second  process. The fracture mechanism for the pre-precipitated δ phase alloy was microvoid coalescence ductile fracture, and the δ phase and carbide were the nucleuses for the formation of micropores. Thus, the existence of the δ phase made the high-temperature plasticity of GH4169 alloy decrease, and the content of the pre-precipitated δ phase must be controlled in the DP of GH4169 alloy.