The invention refers to a battery lock-up device, a new energy vehicle comprising the battery lock-up device, and a method for installing/detaching a power battery. The battery lock-up device comprises: a connection bracket having a first connection hole and a dual limited position structure; a housing structure having a second connection hole; a press plate and a nut, the press plate comprising a head portion and a pillar portion passing through the first connection hole and the second connection hole, the pillar portion being formed with a threaded portion for engaging with the nut and having a distal end adapted to mate with a rotational operation tool; and an anti-rotation locking member which locks the nut against the housing structure. When the press plate is in the first limited position, the press plate and the nut which is engaged on the threaded portion lock-up the connection bracket and the housing structure; and when the press plate reaches the second limited position, the head portion of the press plate can exit via the first connection hole so as to realize unlocking. The invention applies to a situation of detaching and installing the battery quickly. By retaining only the locking function and quick detaching/installing function on the new energy vehicle, the mechanical structure is simplified, arrangement space is reduced, the cost of a single vehicle is reduced, and the reliability is improved.