The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties.The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets.It is found that when the hematite concentrates are pretreated by high pressure roll grinding (HPRG),the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time.The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates,which promotes the hematite concentrate particles to be compacted,the solid-phase crystallization,and finally the formation of Fe2O3 bonding bridges during subsequent high temperature roasting process.