A method of preparing a hydroxytyrosol sturgeon skin gelatin film with antioxidant activity and Salmonella detection ability includes: (1) mixing a neutral red indicator solution and distilled water at room temperature to obtain a mixture solution, and adding 1 mol/L NaHCO3 solution to the mixture solution until discoloration to obtain an alkaline solution; (2) adding an amount of the alkaline solution obtained in step (1) to a mixture of Sturgeon skin gelatin and distilled water to obtain an alkaline gelatin solution; (3) adding hydroxytyrosol and glycerin and propylene glycol to the alkaline gelatin solution to obtain a hydroxytyrosol gelatin solution, and heating the hydroxytyrosol gelatin solution at 40-70° C.; (4) ultrasonicating the hydroxytyrosol gelatin solution from step (3), placing the hydroxytyrol gelatin solution evenly on a clean plexiglass plate, drying the hydroxytyrol gelatin solution on an ultra-clean worktable to obtain the hydroxytyrosol sturgeon skin gelatin film.