A gel electrolytes with high mechanical strength (P(AAPBA-co-AM)) was synthesized, in which 3-acetamidophenylboronic acid (AAPBA) and acrylamide (AM) were used as raw materials, ammonium persulfate (APS) was used as the initiator. The mechanical properties of the hydrogel electrolyte and the electrochemical properties of the supercapacitor based on this hydrogel electrolyte were investigated. The results showed that the synergistic effect of multiple hydrogen bonds between poly3-acetamidophenylboronic acid and polyacrylamide chains made the hydrogel possess good mechanical strength and toughness, with a fracture stress of 170 kPa and a breaking elongation rate of 5 000%. When the current density was 1 A/g, the specific capacitance reached 116 F/g and the capacity retention rate remained 74% after 2 000 cycles. When the supercapacitor was bent and folded, its electrochemical performance basically remained unchanged, showing good flexibility and electrochemical stability.