Abstract: Objective To analyze the effects of different nasal feeding methods and body positions on the concentration of pepsin in saliva of oldest-old patients with long-term nasal feeding. Methods Forty oldest-old patients who underwent nasogastric tube enteral nutrition treatment in our hospital from January to February in 2018 were selected. They were all male patients with age of 80-100 (91.09±4.912) years old. We collected 1 ml saliva in the morning and at 1 hour after lunch, and the pepsin concentration was measured by enzyme-linked immunosorbent assay (ELISA). Taking nasal feeding (pumping and Syringe injection) and body position (semi-recumbent and sitting) as the research factors, the changes of salivary pepsin concentration were compared before and after intervention, and the effects of different nasal feeding methods and body positions on salivary pepsin concentration in oldest-old patients were investigated. Results There was no interaction between nasal feeding and body position (P>0.05). Nasal feeding methods (pumping method and Syringe injection method) played a leading role in the influence of pepsin concentration in saliva of oldest-old patients (P<0.05). Body positions (semi-recumbent position and sitting position) had no effect on the concentration of pepsin in saliva of oldest-old patients (P>0.05). Conclusion Continuous tube feedings by feeding pump is beneficial to reduce the gastro-esophageal reflux in oldest-old patients. The body position (semi-recumbent versus sitting) have no significant effect on salivary pepsin concentration.