Pain is the main complication after TACE(Transcatheter Arterial Chemoembolization) for hepatocellular carcinoma, and its pathogenesis is not clear.The pain may be related to partial liver tissue swelling after blocking the tumor blood supply artery embolization agent, transient hepatic swelling causing tension or strain on the liver capsule, and chemical irritation by the anticancer drug-Lipiodol mixture,the inadvertent embolization of normal organs and individual sensitivity to pain. Ketamine produces anesthetic and analgesic effects mainly by inhibiting NMDA receptor(N-methyl-D-aspartic acid receptor), and previous studies have shown that low concentrations of ketamine have obvious analgesic effects. Not only that, ketamine also produces analgesic effects by inhibiting opioid receptors via G-protein coupling. In addition, ketamine can bind to monoaminergic receptors in the central and peripheral nervous system, showing an anticholinergic effect and producing an antispasmodic effect. Ketamine also inhibits inflammatory pain by reducing nitric oxide production by inhibiting nitric oxide synthase. Esketamine is about three to four times more potent than ketamine. Therefore,esketamine requires a lower dose, about half the dose of ketamine, to produce anesthetic and analgesic effects, with fewer side effects.