The present invention discloses a belt-transmission angle attachment head, including a housing, a power mechanism, a transmission mechanism and a spindle; the power mechanism and transmission mechanism are arranged in the housing; the power mechanism includes a servo motor and a reducer, the servo motor is connected to the reducer, and an input shaft of the reducer is vertically arranged with respect to an output shaft of the reducer; the transmission mechanism includes a driving wheel, a transmission belt and a driven wheel, and the driving wheel is mounted on the output shaft of the reducer; a side of the spindle is mounted on the housing via a rotating shaft, an end of the rotating shaft away from the spindle is mounted with the driven wheel, the driving wheel and the driven wheel are connected via the transmission belt, and the spindle and the power mechanism are located on the same side of the transmission mechanism. The angle attachment head has advantages such as small size, simple structure and suitable for deep cavity machining.