Objective To explore the influencing factors of the quality of gastric mucosal preparation before gastroscopy on the clarity of gastric mucosa under gastroscopy.Methods Clinical data of 240 patients who underwent painless gastroscopy for the first time at the endoscopy center of a tertiary hospital in Wenzhou from September 1,2023 to December 31,2024 were analyzed.The mucosal clarity score under gas-troscopy was recorded during the gastroscopy process,and the influencing factors on the qualification rate of gastric mucosal preparation quality for painless gastroscopy were analyzed.Results The unqualified rate of gastric mucosal preparation in patients undergoing painless gastroscopy was 52.9％,with the highest rates in the upper part of the stomach(17.1％)and the bottom of the stomach(12.1％),followed by the lower part of the stomach(9.2％),the antrum(7.9％)and bulb(3.8％),the lowest rates in the esophagus(2.9％).The quality of gastric mucosal preparation was relatively poor.Multivariate logistic regression analysis showed that,BMI,Helicobacter pylori(Hp)infection,abnormal gastric juice characteristics,and gastric polyps were independent risk factors affecting gastric mucosal preparation(OR=2.784,3.501,3.873,3.611,P＜0.05).Conclusion Insufficient preparation of gastric mucosa is associated with high BMI,Hp infection,abnormal gastric juice characteristics,and gastric polyps.To address patients with these risk factors,individualized pre-treatment plans should be developed based on routine fasting to optimize endoscopic field of view and ensure examination quality.