The relationship between the high-temperature creep behavior and microstructure of an Fe–Ni–Cr–W–Al alloy used as the centrifugal casting material for the radiant section tubes of ethylene pyrolysis furnaces was investigated, along with the precipitate phases. Analyses were performed using a high-temperature creep testing machine, OM, SEM, TEM, and other instruments. The creep behavior was evaluated at 900–1200 ℃ and 10–48 MPa. The data reveal that the as-cast microstructure of the 27Cr44Ni5W3Al+MA alloy consists of γ and eutectic precipitates, where the eutectic precipitates mainly comprise herringbone-shaped M₇C₃ and blocky or lamellar M₂₃C₆, as well as coherently precipitated, dispersed γ′ particles and a small number of blocky γ′ particles within the γ matrix. A plot of the Larson-Miller parameters indicates that this alloy has excellent creep performance, where the high-temperature creep data fit a master curve according to the relation lgs = 3.67436 –0.04401P–0.00121P². As the temperature in the creep test increases, the average widths of the M₇C₃ and M₂₃C₆ precipitates gradually increase from 0.9 and 4.6 μm for the original as-cast state to 1.8 and 8.1 μm at 1200 ℃, respectively. During the creep process at 900℃–1050℃ and 10–48 MPa, M₇C₃ is gradually transformed into blocky M₂₃C₆, which precipitates with blocky γ′. The precipitation of γ′ is most pronounced at 950 ℃ and the average particle width also increases from 1.4 μm for the as-cast state to 3.3 μm. The creep cavities mainly nucleate at the interfaces between the coarse, blocky M₂₃C₆, blocky γ′, and thin, lamellar M₇C₃ eutectic precipitates and the γ matrix. During the creep process at 1100℃–1200℃, M₇C₃ is further transformed into blocky M₂₃C₆, with no observed precipitation of blocky γ′. The creep cavities undergo further nucleation at the interfaces of the coarse, blocky M₂₃C₆ or thin, lamellar M₇C₃ eutectic precipitates with the austenite matrix, all of which are intergranular fractures.