The present invention is applicable to the field of electronic device technologies, and discloses an antenna structure and a mobile terminal device. The antenna structure includes a housing and a feed plate, where the housing includes a main housing, a first floating object, a second floating object, and an antenna radiator, and the first floating object, the second floating object, and the antenna radiator are all disposed on one side of the main housing and are separated from the main housing by a first isolation slot; the first floating object is disposed on one side of the antenna radiator and is separated from the antenna radiator by a second isolation slot; the second floating object is disposed on the other side of the antenna radiator and is separated from the antenna radiator by a third isolation slot; the main housing, the first floating object, the second floating object, and the antenna radiator are connected as a whole by an insulator; and the feed plate is disposed opposite to the main housing, the first floating object, and the antenna radiator at an interval. The mobile terminal device has the foregoing antenna structure. The antenna structure and the mobile terminal device with the antenna structure that are provided in the present invention ensure an all-metal housing feature of the mobile terminal device, and the structure is simple and costs are low.