Abstract: Using the high shear mixing emulsifying machine to replace the ordinary mixer，nano-sized barium sulfate was modified by means of wet reaction.The effect of emulsifying time，emulsifying temperature，dosage of modifier，and solid content of nano-sized barium sulfate suspension on the activation degree of the modified nano-sized barium sulfate was also investigated.The coating situation and the morphology of the modified nano-sized barium sulfate were characterized by infrared spectrometer，thermogravimetric analyzer，and scanning electron microscope.Experimental results showed that hydrophobic nano-sized barium sulfate powder with activation degree of 99.88% and oil absorption value of 0.497 5 g/g could be obtained with the high shear mixing emulsifying machine，when emulsifying time was 15 min，emulsifying temperature was 65 ℃，dosage of modifier was 5%（(mass fraction），and solid mass concentration of suspension was 100 g/L.

Key words: emulsification machine, nano-sized barium sulfate, modification