The invention relates to a high-luminous-flux spectrograph based on a partitioned digital micro-mirror. The partitioned digital micro-mirror in the spectrograph comprises two micro-mirror array regions which are modulated by codes respectively: a first micro-mirror array region and a second micro-mirror array region; light emitted by a light source passes through a collimation lens and then reaches a light splitting device; a first converging lens is arranged at an outgoing light path of the light splitting device; the first micro-mirror array region of the partitioned digital micro-mirror is arranged on an outgoing light path of the first converging lens and a second converging lens is arranged on the outgoing light path when the first micro-mirror array region is at an open state; a reflecting mirror is arranged on the outgoing light path when the first micro-mirror array region is at a closed state; the second micro-mirror array region of the partitioned digital micro-mirror is arranged on the outgoing light path of the reflecting mirror; a third converging lens is arranged on the outgoing light path when the second micro-mirror array region is at the open state; and a single-point detector is located at focal points of the first converging lens and the second converging lens at the same time. The high-luminous-flux spectrograph based on the partitioned digital micro-mirror, provided by the invention, has relatively high luminous flux, is compact in structure and is low in production cost.