In a 3L four-necked flask equipped with stirring, reflux tube and thermometer, 106g (1mol) of o-xylene and 107mL (1.97mol) of 98% concentrated sulfuric acid were added, and then heated at 100 for 1.5h with stirring, and cooled to room temperature. Add 1500mL of water and stir to dissolve, then neutralize with 473g of barium hydroxide hydrate and 750mL of water under stirring to pH 7. Filter while hot, pour the filtrate into a 3L three-mouth flask, add 192g of bromine (1.2mol), 200g of barium bromide and 700mL of water under stirring at 50~60 and stir to react for 15h at 50~60, then cool, filter and add 200mL of water200g of barium bromide, and then cool and filter. Then cooled, filtered, washed with water 200mL2, dried in vacuum, obtained 3-bromo-o-xylene sulfonic acid barium salt about 231g, yield 69%.
