A door handle lock and a locking method are provided. The door handle lock comprises a first lock body, a second lock body, and a locking part, and the locking part is engaged with a movable part to lock the first lock body, thus being difficult to unlock. The door handle lock is mounted within a rotation range of the door handle, and the rotation of the door handle is limited by the first lock body. Such a setting effectively prevents a child from unlocking without permission and then opening the door to escape, thus improving the security.