A secondary battery, including an electrode assembly, a positive terminal, a negative terminal, a top cover plate, a conductive plate and a contact plate, wherein the electrode assembly includes a positive electrode plate, a negative electrode plate and a separator provided therebetween, the positive electrode plate is electrically connected with the positive terminal, and the negative electrode plate is electrically connected with the negative terminal, the contact plate is attached to the negative terminal, the top cover plate is insulated from the negative terminal and is electrically connected with the positive terminal, the conductive plate is fixedly connected with the top cover plate, the contact plate is configured to deform under gas pressure to be in contact with the conductive plate when an internal pressure of the secondary battery exceeds a reference pressure.