On January 6, the phthalic anhydride market in Shandong showed an upward trend. The mainstream negotiated price for ortho-xylene-based phthalic anhydride was 5,900–6,150 yuan/ton, while the mainstream negotiated price for naphthalene-based phthalic anhydride was 5,600–5,850 yuan/ton. The price of raw material ortho-xylene rose sharply, while the price of industrial naphthalene remained stable. The cost of phthalic anhydride increased, and the downstream plasticizer market experienced a strong upward trend. The operating rates of phthalic anhydride plants declined, leading to a reduction in the overall operating rate of phthalic anhydride enterprises. Despite ample supply in the phthalic anhydride market, the operating load of plasticizer enterprises decreased. However, rigid demand for phthalic anhydride remained, and the market outlook for phthalic anhydride is expected to continue its strong upward trend.