To evaluate the therapeutic effect of Magnolol on Aeromonas hydrophila infections, the effects of magnolol on infection results, blood biochemical indexes, liver antioxidant factors, tissue pathology, and inflammation-related gene expression were analyzed based on the construction of a Carassius auratus gibelio infection model. Blank control, infection group, and 2 mg/kg, 8 mg/kg, and 32 mg/kg magnolol treatment groups were set up. The results showed that magnolol treatment could effectively reduce mortality in infected fish, with relative protection rates of C. auratus gibelio treated with magnolol at 60.75%, 71.85%, and 59.95%, respectively. Compared with the infection group, in the treatment groups, ALT, AST, and LDH were significantly decreased, TP and ALB content was significantly increased (P<0.05), CAT and SOD activities were significantly increased, GSH content was significantly increased, and MDA content was significantly decreased (P<0.05). Histopathological results showed that honokiol alleviated congestion of the liver and spleen to some extent and reduced cell necrosis in the kidneys and intestines. In terms of the expression of inflammation related genes, magnolol treatment significantly decreased the expression of MyD88, NF-κB, and TNF-α but significantly increased the expression of TLR-5 (P<0.05). These results indicate that magnolol can reduce mortality from A. hydrophila infections in allogynogenetic crucian carp, reduce oxidative tissue damage, and downregulate the expression of inflammationrelated genes. The results provide a theoretical basis for the application of magnolol in commercial applications.