Abstract: Sinter from the transfer system between the 300 m² sintering machine and the 1 260 m³ blast furnace at Jianlong Xilin Iron and Steel Co., Ltd. was taken as the research object. Full-process tracking sampling, industrial computed tomography (CT) three-dimensional reconstruction, scanning electron microscopy, and non-standard metallurgical performance tests were employed to systematically analyze the evolution patterns of particle-size distribution, tumbler strength, pore structure, crack propagation, and metallurgical properties of sinter during transfer. The results indicate that sinter particle refinement is induced by repeated high-head falling and mechanical collisions during transfer. The proportion of large-size fractions exceeding 25 mm is significantly reduced, whereas the proportion of the 5,10) mm fraction is gradually increased, and a refinement trend is exhibited by the average particle size. As revealed by industrial CT three-dimensional reconstruction, the internal pores, initially present as tiny and dispersed closed pores, are progressively transformed into interconnected fracture networks. Fracture length and connectivity are markedly increased, structural integrity is continuously deteriorated, and large-area interwoven cracks are formed prior to blast furnace charging. Tumbler strength is locally elevated due to the retention of high-strength large-size sinter fractions. Reducibility is found to decrease first and then increase. Low-temperature reduction degradation index is obviously deteriorated in the middle-to-late stage of transfer, which is attributed to the uniform pore structure formed by medium-size sinter fractions. Gas diffusion conditions can be improved and the reduction degree can be enhanced by such a pore structure.