In order to explore the effect of coal gangue powder on the properties of modified magnesia sulfide cement before and after calcination，coal gangue powder was firstly calcined at different temperatures（0，600，800 ℃），and then mixed as aggregate to prepare modified magnesia sulfide cement，and X-ray diffraction，scanning electron microscopy and mercury injection instrument were used to test the phase composition，microscopic morphology and porosity of the cement.The effects on mechanical properties，water and acid resistance，micro-morphology and pore structure of modified magnesium sulfide cement were analyzed.The test results showed that the addition of coal gangue powder calcined at 800 ℃ could improve the compressive strength of the modified magnesium sulfide cement.When the addition amount was 15%，the maximum compressive strength of the cement at 28 days，which was 130% of the reference sample.At the same time，the water and acid resistance of the cement could be improved.The addition of coal gangue powder could improve the microstructure of modified magnesia sulfide cement，promote the growth of 5·1·7 phase，and make the morphology more dense.20%EG/MOS after leaching，the proportion of pore size greater than 100 nm was decreased，and the proportion of pore size less than 10 nm was increased，indicating that the addition of coal gangue powder calcined at 800 ℃ mass 20% could resist the penetration and dissolution of water and acidic liquid，and strengthen the water resistance and stability of the cement.