Abstract: A series of compression tests are conducted on iron ore tailings taken from Qingshan tailings impoundment to analyze the compression deformation behavior. Furthermore, the scanning electron microscopy (SEM) tests and mercury intrusion porosimetry (MIP) tests are carried out on post-test specimens to study the effects of microstructure on compression deformation properties of iron ore tailings. The compression test results show that the iron ore tailings exhibit basically consistent compression behavior during uniaxial compression and isotropic compression. Different initial dry densities are found to have few effects on the shape and slope of compression curve but change the initial void ratio. The specimens with single size gradation show stronger compressibility than those with design size gradation. The microscopic tests results show that pore structure of the iron ore tailings is various and complicated, and the pore sizes are mainly distributed in the interval of 10 to 0.1 μm. Both the initial dry density and the consolidation pressure affect the total porosity of the iron ore tailings, and the later one has more severe effect. The research results may provide reference for the design, operation and maintenance of tailings impoundment.