In this paper, through the creep performance test, microstructure morphology observation and composition analysis of a new type of nickel-based single-crystal superalloy under the condition of 1100°C/140 MPa, the variation characteristics of the creep rate and the evolution characteristics of the microstructure before and after creep during the creep fracture process of the alloy were investigated, and the creep fracture mechanism of the new nickel-based single-crystal superalloy was revealed. The results indicate that the creep life of the alloy is 104.5 h, the strain can reach 33.58%, the creep rate decreases first and then increases, and finally tends to be stable until fracture. At the initial stage of creep, the creep rate shows a phenomenon of decreasing first, then rising and then decreasing again with time. Furthermore, the creep fracture microstructure is composed of dimples and tearing edges, without obvious slip planes. Oxides and recrystallized structures exist inside the fracture surface, and the voids inside the fracture are elongated and perpendicular to the stress axis, showing a fracture mechanism of microcrack accumulation.