Abstract: The reasons of ultrafine hematite worsen reverse indices leading to higher grade of flotation tailing were investigated via characteristics research of in-situ flotation product, flotation tests of mixed ores and micro adsorption percent determination, as well as SEM and EDS. It was shown that the main parts resulting in higher grade of tailing was -0.010mm with yield of 23.11%, iron minerals dissociation degree of 80.43% and metal distribution up to 31.08%. Mixed minerals flotation results indicated that hematite size worsen reverse flotation indices most slightly when the content of -0.010mm hematite was 40%. Micro adsorption tests showed that adsorption between hematite and quartz occurred with smaller probability when hematite sizes were near to that of quartz and the content of hematite and quartz was different notably, or both sizes of hematite and quartz were similar and hematite content was 40%.