Abstract: Systematically studied the chemical composition，mineral composition，main mineral dissemination characteristics and dissemination size of ores from Sijiaying Iron Ore Mine first-stage opencast.Based on the analysis of techno-mineralogical properties and washability，the ores in opencast are divided into three types：easy to disintegrate and easy to select，easy to disintegrate and hard to beneficiate，hard to disintegrate and hard to beneficiate.And analyze the mining selectivity of the three types，identify their distribution as well.These investigation results provide ways for optimizing the mineral processing technology，and can be a useful reference for developing this type of iron ores.

Key words: Technological mineralogy, Dissemination size, Washability