Delirium in the late stage of bile duct cancer may be due to brain metastasis, pain, taking drugs. 1. Brain metastasis: usually, the cancer cells in the late stage of bile duct cancer can be metastasized. When the cancer cells metastasize to the brain, it will cause the tumor to press the brain nerves, which will cause the patient to have consciousness disorder and lead to delirium. 2. Pain: Usually, late-stage cholangiocarcinoma will cause persistent severe pain or intermittent severe pain, which is mainly due to the tumor’s pressure on body organs and nerves. This kind of pain is usually unbearable, so when the pain is severe, the patient may become delirious or even comatose. 3. Taking drugs: patients with advanced stage of cholangiocarcinoma will take strong painkillers to relieve pain, and some drugs will also cause patients to have delirious symptoms. 4. Extremely weak body: when the patient’s condition enters the advanced stage and is in the state of malignant disease, the nutrition supply of the body is extremely scarce and the blood pressure is unstable, so the patient may have delirium. Patients with advanced stage of cholangiocarcinoma should go to hospital for examination and treatment in time if they have any physical discomfort, so as to avoid delaying their condition.