A secondary battery, including a first terminal assembly, a second terminal assembly, a top cover plate, an electrode assembly and a first sealing piece; at least one of the first and second terminal assemblies is electrically insulated from the top cover plate; the first terminal assembly includes a connecting plate and deformable plate, the connecting plate is located at a side of the top cover plate away from the electrode assembly, the deformable plate is attached to the connecting plate; the first sealing piece is connected between the connecting plate and the top cover plate; in normal state, the first electrode plate is electrically connected with the connecting plate via the deformable plate, the second plate is electrically connected with the second terminal assembly; when internal pressure of the secondary battery exceeds reference pressure, the deformable plate can deform to electrically disconnect from the first electrode plate.