On January 5th, the market price of phthalic anhydride in East China showed an upward trend. The mainstream quotation for phthalic anhydride produced via the ortho-xylene method was 5,800–6,100 RMB/ton, while the market price for phthalic anhydride produced via the naphthalene method ranged from 5,500 to 5,800 RMB/ton. The price of industrial naphthalene fluctuated but tended to stabilize, while the price of ortho-xylene rose strongly, leading to an increase in the cost of phthalic anhydride. Downstream, the plasticizer market experienced a robust upward trend, with plasticizer manufacturers reducing their equipment operating rates. Downstream demand remained rigid, with procurement of phthalic anhydride primarily based on immediate needs. Despite this, demand support for phthalic anhydride persisted. Phthalic anhydride manufacturers slightly reduced their equipment operating rates, but supply remained sufficient, and inventory levels were low. It is expected that the phthalic anhydride market will maintain a strong consolidation trend in the near future.