The invention discloses a chair bed, which comprises a berth, a backrest, a berth locking device and a backrest locking device. The berth consists of a berth body, berth mounting seats and berth shafts, the berth mounting seats are mounted on walls at two ends of the berth so that the berth is supported, one end of each berth shaft is embedded in the corresponding berth mounting seat, and the other ends of the berth shafts are embedded at two ends of the berth body; the lower end of the backrest is hinged with two edges of a seat surface of the berth; the backrest is positioned on the lower portion of the berth when folded with the berth, the berth and the backrest are locked by the backrest locking device, and the berth is locked by the berth locking device; and after the berth drives the backrest to turn over, the backrest is positioned on the upper portion of the berth, the berth is locked by the berth locking device, and the backrest is upwards turned to be opened. By the aid of the chair bed, functions of a berth and functions of a seat can be realized, two options are provided for a passenger, and embarkation comfortableness is improved.