A hinge comprises a rotatable bracket, a fixed bracket, a torsion spring, a locknut element and a shaft penetrating through the rotatable bracket, the fixed bracket, the spring and the locknut element. The rotatable bracket forms a through hole therein. The hinge further comprises an elastic hook and a driving element. The elastic hook is inserted into the through hole of the rotatable bracket to lock the electronic device when the electronic device is closed. A driving element mounted in the main body receives an operation of the user to push the elastic hook out of the through hole in order to open the electronic device.