Abstract: In the present study, agar-sodium alginate bilayer films were prepared with ginger essential oil (GEO) as the antibacterial agent. Representative water-based and fatty food simulation solvents were selected for immersion and unilateral release experiments of the films to explore the behavior of essential oil diffusion and release from the film matrix. In addition, four classical mathematical models were selected to fit the primary release mechanism of GEO. The effect of the antibacterial film on the microbial quality of grass carp during refrigeration was evaluated. The results showed that the immersion release and unilateral release of GEO in simulated solvents (distilled water, 10% v/v ethanol, 50% v/v ethanol, and 95% v/v ethanol solution) for water-based and fatty foods exhibited a behavioral pattern of rapid release, followed by stable and sustained release, which could enable the achievement of good sustained release from the film matrix. The model fitting results of the GEO release behavior indicated that the GEO release from the film matrix was primarily based on Fickian diffusion, and that the Peppas-Sahlin model could better explain its release mechanism, followed by the Peleg model. The results of the refrigeration of grass carp showed that the antibacterial effect of GEO on the bilayer film and its rapid and sustained slow release from the film matrix could effectively inhibit microbial growth and production of volatile salt based nitrogen compounds of the grass carp, and based on the comprehensive detection results of sensory, physicochemical, and microbiological indicators, it was found that the addition of GEO could extend the shelf life of grass carp with the agar-sodium alginate bilayer film packaging by approximately 3 d during refrigeration compared with the PE treatment group and the control group without packaging.