Abstract: Objective To study the effects of positive acceleration adaptive training on the lesion index and PGE₂ingastric mucosa of rats. Methods Forty male SD rats were randomly divided into 5 groups: A, B, C, D and E, 8 rats in each group. group A was the control group without any treatment. group B was exposed to +5gz for 5 minutes per day over 5 consecutive days. group C was exposed to +10gz for 5 minutes per day over 5 consecutive days. group D was exposed to +4gz for 3 minutes per day over 5 consecutive days and +5gz for 5 minutes per day over another 5 consecutive days. group E was exposed to +4gz for 3 minutes per day over 5 consecutive days and +10gz for 5 minutes per day over another 5 consecutive days.Then the damages to thegastric mucosa were observed with naked eye and the lesion indexes (LI) were calculated.The PGE₂contents in thegastric mucosa were detected by ELISA. Results On unaided visual observations, all groups developed mucosa damage except group A.The lesion index was significantly higher in group C than group B (5.625±1.767) vs (1.750±0.707), P＜ 0.05.After adaptive training, the lesion index was significantly lower in group D than group B (0.875±0.641) vs (1.750±0.707), P＜ 0.05, and it was significantly lower in group E than group C (2.250±1.035) vs (5.625±1.767), P＜ 0.05.The content of PGE₂was significantly lower in group C than group B (24.598±6.017) pg/ml vs (60.468±9.697) pg/ml, P＜ 0.05.After adaptive training, the content of PGE₂was significantly higher in group E than group C (46.165±13.996) pg/ml vs (24.598±6.017) pg/ml, P＜ 0.05. Conclusion Low speed +Gz adaptive training can significantly reduce thegastric mucosal damage caused by high speed +Gz, and its mechanism is related to the increase of PGE₂.