Abstract: In response to the urgent demand for highly adhesive and environmentally friendly quasi-solid electrolytes for flexible zinc-air batteries, self-adhesive and degradable quasi-solid hydrogel electrolytes with a three-dimensional network structure were synthesized through the construction of a composite system of dopamine graft-modified sodium alginate (SA-DA) and gelatine combined with a temperature-induced gelation and a synergistic cross-linking strategy of Zn²⁺/NH₄⁺ (Gelatin/SA-DA). It was shown that the Gelatin/SA-DA1.0 hydrogel electrolyte exhibited synergistically enhanced mechano-electrochemical properties when SA-DA was added at an amount of 1.0 mL: its tensile stress was up to 70 kPa (strain>250%), its interfacial adhesion strength to the carbon cloth and zinc electrodes was 36 and 20 kPa, respectively, and its ionic conductivity reached 24.28 mS·cm⁻¹. Meanwhile, the flexible zinc-air battery assembled based on the Gelatin/SA-DA1.0 hydrogel electrolyte has a high power density (26.84 mW·cm⁻²) and good cycling stability. In addition, the hydrogel electrolyte can be completely degraded in 3 mol·L⁻¹ H₂SO₄ solution within 60 min, and its rapid and controllable degradation characteristics provide a new idea for solving the waste disposal problem of flexible energy storage devices.