Paraquat poisoning usually results in a series of multiple organ function damage, but the most serious damage is pulmonary fibrosis, which is basically irreversible and has a high mortality rate when the patient is in pulmonary fibrosis, so it is the most serious damage. After paraquat poisoning, patients will gradually develop pulmonary fibrosis within one month. Patients will have coughing, coughing and progressive dyspnea, which will be significantly aggravated after activities, and they will show signs of oxygen deprivation such as purple nails, cyanosis and restricted activities, and they will also have weakness around the body and poor food intake. The most serious damage is pulmonary fibrosis until the end of paraquat poisoning when the patient develops uncorrectable hypoxemia and must be treated with ventilator.