Objective The aim of this study was to establish an acute gastric mucosal injury (AGMI) rat model induced by hydrochloric acid ( HCl) at different concentration gradients and to investigate the effects of intravenous injection of evans blue (EB) at various concentrations and dosages on survival rate and superficial extravasation. Methods (1) Wistar rats were randomly assigned to five weight-based groups: 150 ~ 180 g, 180 ~ 200 g, 200 ~ 250 g, 300 ~400 g, 400 ~ 500 g. Each group was further subdivided into eight subgroups based on HCl concentration, specifically:0. 40, 0. 45, 0. 50, 0. 55, 0. 60, 0. 65, 0. 70 mol / L HCl, along with a control group treated with saline. This result ed in a total of 40 subgroups, with three rats per subgroup, summing up to 120 animals in total. The survival rate of rats 24 hours post-modeling was assessed, and the interaction between body weight and HCl concentration on rat survival was analyzed. Following the establishment of five graded HCl concentrations, gastric mucosal pathological changes were observed microscopically using hematoxylin-eosin staining (HE) staining. (2) From these result, the highest suitable concentration of HCl was selected to prepare the AGMI model. Subsequently, rats were randomly allocated into different groups based on the concentration and dose of EB, specifically: EB 1 (0. 5%, 0. 4 mL), EB 2 (1%, 0. 1 mL/ 100 g), EB 3 (1%, 0. 2mL/ 100 g), EB 4 (2%, 0. 1 mL/ 100 g), EB 5 (2%, 0. 2 mL/ 100 g), and EB 6 (5%, 0. 1 mL). Each group consisted of five rats, totaling 30 animals. The survival rate and extent of dermal exudation were evaluated 24 hours post-injection of EB. Results (1) Post-modeling symptoms in AGMI rats intensified with increasing concentrations of HCl, with the 24- hour survival rate in all weight groups being 0% for both 0. 65 mol / L and 0. 70 mol / L HCl. Kaplan-Meier survival curves indicated significant differences in survival rates among rats in different HCl concentration groups ( P<0. 001 ).Furthermore, a significant interaction effect between HCl concentration and body weight on rat survival time was observed(P<0. 001 ). The five gradient HCl concentrations established were from 0. 40、 0. 45、 0. 50、 0. 55、 0. 60 mol / L.Histological observations revealed that the degree of inflammatory cell infiltration in the gastric mucosa of AGMI rats escalated with increasing HCl concentrations. (2) AGMI rats prepared with 0. 60 mol / L HCl and injected with 5% EB (0. 1 mL) had a 24 h survival rate of only 40%. Kaplan-Meier survival curves showed no significant differences in survival rates among AGMI rats under different concentrations and dosages of EB (P>0. 05). Analysis of superficial extravasation revealed that skin and eye color were lighter in EB 1 group rats, with fewer extravasation points, while rats in EB 4 and EB 5 groups exhibited more apparent skin color changes and extravasation. One-way ANOVA further confirmed that the number of superficial EB extravasation points in the EB 3, EB 4, and EB 5 groups was significantly higher than that in EB 1 group (P<0. 05, P<0. 01). Conclusions HCl modeling successfully achieved a setting of multiple precise concentration gradients. Gastric lavage with HCl concentrations ranging from 0. 40 mol / L to 0. 60 mol / L in rats with a fasting body weight of 180 ~ 200 g was used to successfully prepare an AGMI model. Intravenous injection of 2% EB (0. 2 mL/ 100 g) can facilitate the study and analysis of the distribution characteristics of superficial EB extravasation points in AGMI rats over time and as the condition progresses.