Abstract: The mineral composition and microstructures of pellets are important factors affecting their metallurgical properties.The mineral types,contents,morphology,size,distribution and pore characteristics of acid pellets from different steel works were quantitatively studied by polarizing microscope and X-ray diffraction,and metallurgical properties were tested.The fundamental reason for the mineral phase structure of acid pellets affects the quality of pellets was discussed.The results show that microstructures of acid pellets in Hangang,Tanggang and Chenggang steel mills are relatively uniform.They are mainly cemented by magnetite,hematite and iron olivine with better compressive strength.The compressive strength of Pangang's pellets is the lowest,and the corresponding microstructures are not uniform.The outer zone is dominated by the granular structure of ilmenite hematite,while the internal zone is mainly composed of titanomagnetite corrosion structure,and the connectivity between metal phases is weak.The microstructures of Chenggang's pellets are mostly uniformly distributed and have good connectivity between the pores.The reducibility of the Chenggang's pellets is obviously better than the those of other pellets.