In carbon monoxide poisoning, carboxyhemoglobin in blood can be measured, and electroencephalogram, cranial CT and electrocardiogram can also be performed, as follows; 1. Measurement of carboxyhemoglobin in blood; carboxyhemoglobin in blood is higher than 10% in mild carbon monoxide poisoning, higher than 30% in moderate poisoning and higher than 50% in severe poisoning; 2. Electroencephalogram: abnormalities can be found in patients with acute carbon monoxide poisoning EEG, which shows an increase in low amplitude slow waves; 3. Brain evoked potential examination; 4. Brain imaging: cranial CT examination in patients with carbon monoxide poisoning in the acute phase, or when late onset encephalopathy occurs, abnormal changes can be seen; 5. Laboratory tests: the total number of peripheral blood erythrocytes, total white blood cells and total neutrophils are increased, and cerebrospinal fluid pressure and routine are mostly normal. Blood gas examination shows normal partial pressure of blood oxygen, blood oxygen saturation may be normal, blood pH is reduced or normal, and partial pressure of carbon dioxide in blood often has compensatory decrease; 6. ECG examination.