Embodiments of the present application disclose a secondary battery including an electrode assembly, a packaging bag and an electrode lead. The packaging bag includes a first packaging film and a second packaging film, the electrode assembly is disposed between the first packaging film and the second packaging film. The first packaging film and the second packaging film each include a main body portion, two extending portions and two connecting portions, the main body portion is located on one side of the electrode assembly in a thickness direction, the two connecting portions are respectively located on two sides of the electrode assembly in a transverse direction, the two extending portions respectively extend from two ends of the main body portion in the transverse direction and are respectively connected to the two connecting portions. Each extending portion includes a first arc region, an inclined region and a second arc region.