The invention discloses an active magnetic regenerator and a magnetic refrigeration system. The active magnetic regenerator comprises a shell, a rotating mechanism and a magneto-thermal unit, wherein the rotating mechanism and the magneto-thermal unit are arranged in the shell; the rotating mechanism comprises a rotating part and a fixed support, and the fixed support is arranged on the inner wall of the shell through the rotating part; and the magneto-thermal unit comprises a plurality of plate-shaped magneto-thermal materials which are arranged in parallel, and the magneto-thermal units are arranged on the fixed support. According to the active magnetic regenerator, the magneto-thermal unit is arranged inside the shell through the rotating mechanism, when the direction of an external magnetic field changes, the magneto-thermal unit synchronously rotates with the external magnetic field under the action of magnetic torque so that the direction of the external magnetic field can be always kept in the direction with the smallest demagnetization factor of the magneto-thermal materials, magnetic fields in the magneto-thermal materials are ensured to be maximized, the magneto-thermal effect of the magneto-thermal materials is fully exerted, and the optimal refrigerating performance is obtained. Meanwhile, under the action of the magnetic torque, the magneto-thermal unit rotates, so that large alternating stress is avoided inside the magneto-thermal materials, and the service life of the whole regenerator is prolonged.