Slight thickening of the lower esophageal mucosa may be caused by esophagitis, abnormal hyperplasia of the esophageal mucosa, esophageal space-occupying lesions and other factors. 1. Esophagitis: the esophageal mucosa is often damaged by gastric acid, strong acid and alkali, drugs, infection, immunity and other factors, causing inflammatory changes such as congestion and edema. Gastroscopy can show a slight thickening of the lower part of the esophageal mucosa, and patients may have symptoms such as acid reflux, heartburn, abdominal distension, abdominal pain, and so on. 2. Abnormal hyperplasia of esophageal mucosa: patients are often accompanied by esophageal reflux disease, when reflux occurs, gastric acid will cause damage to the esophageal mucosa, resulting in edema and congestion of the esophageal mucosa. Long-term inflammatory stimulation will lead to hyperplasia in the esophagus, which can also be manifested as a slight thickening of the lower part of the esophageal mucosa. 3. Esophageal space-occupying lesions: Slight thickening of the lower esophageal mucosa may also be related to esophageal space-occupying lesions such as esophageal cancer. When thickening of the submucosal segment of the esophagus occurs, timely consultation should be made, and tissue biopsy is preferred to find out the cause of the disease.