Directionally solidified Ni-based superalloy DZ411 has emerged as a leading material for manufacturing gas turbine engine blades due to its exceptional high-temperature mechanical properties, including superior creep resistance and thermal stability. This study focuses on investigating the creep behavior of DZ411, with particular attention to whether the unique progressive increase in grain size along the casting direction affects the creep properties. A series of creep experiments were conducted to systematically analyze the influence of grain size distribution on the material’s high-temperature creep performance. Controlled testing conditions were employed to elucidate the relationship between grain size and creep resistance. The results reveal that grain size heterogeneity plays a critical role in determining the mechanical stability of DZ411 under prolonged thermal and mechanical stress. These findings provide valuable insights into the microstructural mechanisms governing creep behavior in directionally solidified superalloys, offering a scientific basis for optimizing high-temperature materials in industrial applications. This research not only enhances the understanding of DZ411’s performance but also contributes to the development of next-generation turbine blade materials for advanced gas turbine engines.