Isophthalic acid (IPA), also known as 1,3-phthalic acid or isophthalic acid, has strong heat resistance, hydrolysis resistance and chemical resistance, and can undergo salt formation, dehydration, hydrogenation, halogenation and other reactions. Its biggest use is as an intermediate chemical book in the production of unsaturated polyester resins, followed by the manufacture of polyester resins, alkyd resins (mainly used in coatings) and printing inks. In addition, it can also be used to reinforce plastics and packaging, manufacture film colorants, coatings and polyester fiber dyeing modifiers, and medicines, etc., and has broad prospects for development and utilization.