Abstract: The mineral structure of sinter with medium and high titanium content was studied quantitatively by means of polarization microscope.Observations indicates that titanium hematite and titanomagnetite are the main metallic phases in this two sinter,and the binder phases are calcium ferrite,dicalcium silicate and glassy.And perovskite appears in high titanium sinter.The presence of perovskite not only weakens the continuous crystal effect of iron oxide,but also reduces fraction of the binder phase,which results in low temperature reduction degradation of high titanium sinter.Medium titanium sinter has larger amount of titanium hematite than high titanium sinter,therefore it has better reducibility.When the whole structure of sinter is uniform,its structure type determines the strength.The drum strength of medium titanium type sinter with interwoven structure is higher than that of high titanium type sinter with granular structure.It is suggested that the sintering atmosphere should be controlled reasonably and the formation of good structure should be ensured in order to reduce the negative effect of perovskite.