At present, blast furnace ironmaking is still the main process for producing molten iron, and sinters are the main raw material for blast furnace ironmaking. A sinter with good metallurgical performance can not only ensure smooth operation of the blast furnace but also reduce the blast furnace fuel ratio and increase the molten iron production. Structure is the most important factor affecting the metallurgical properties of the sinter. Thus, the research progress of sinter pore and mineral phase structures was reviewed and the mechanism by which they influence sinter properties was expounded. Multiscale characterization methods for the sinter and their advantages and disadvantages were introduced, and the future research direction of sinter was discussed.