It is a chemical commodity, named Pure terephthalic acid (PTA) in English, and purified terephthalic acid in Chinese, alias PTA. PTA is a low-end product of petroleum. After a certain process, petroleum produces light gasoline (alias naphtha), from which MX (mixed xylene) is extracted, and then PX (p-xylene) is extracted. PTA uses PX (65%-67%) as raw material, acetic acid as solvent, and air oxidation (35%-33% oxygen) under the action of catalyst to produce crude terephthalic acid. Then the crude terephthalic acid is hydrofined to remove impurities, and then the refined terephthalic acid product, namely PTA finished product, is obtained through crystallization, separation and drying.