On January 12, the phthalic anhydride market in Shandong region showed a strong upward trend. The mainstream negotiated prices for o-xylene-based phthalic anhydride were 6,100–6,350 yuan/ton, while those for naphthalene-based phthalic anhydride were 5,700–6,050 yuan/ton. The price of raw material o-xylene rose significantly, while the price of industrial naphthalene remained stable. The cost of phthalic anhydride increased, and the downstream plasticizer market experienced strong consolidation. The operating rates of phthalic anhydride plants declined, leading to a decrease in the overall operating rate of phthalic anhydride enterprises. Despite ample supply in the phthalic anhydride market, the operating load of plasticizer enterprises also decreased. However, rigid demand for phthalic anhydride remained supportive. Looking ahead, the phthalic anhydride market is expected to continue its strong upward trend.