A new process for the production of purified terephthalic acid (PTA) is disclosed to keep terephthalic acid (TA) in dissolved state during the process of oxidation reaction, to obtain intermediate product crude terephthalic acid (CTA) not containing the two impurities of 4-carboxyl benzaldehyde (4-CBA) and p-methyl benzoic acid (PT acid), so that it can eliminate the “purified” production process, and reduce the consumptions of raw materials, acetic acid, fuel and power, and water, thereby saving production costs.