The present invention discloses an angular displacement spectrum device aiming at dynamic coal gangue recognition, pertaining to the technical field of full-mechanized caving mining automatic control.The device is arranged at the inner side of a tail beam of a hydraulic support. The device comprises light wave probes, a spectrometer, optical fiber light sources, an optical switch and a light waveprobe control device. Each light wave probe is connected with an optical fiber light source correspondingly, the two light wave probes can perform optical path switching via the optical switch, and at the same time of the optical path switching, the swing direction of the corresponding light wave probe is changed via the light wave probe control device. Light wave signals are alternately and continuously acquired along the coal/ rock flow direction, and the signals are transmitted to the spectrometer. According to the angular displacement spectrum device, a single chip computer is adopted asthe core controller, the frequency and the duty cycle of the PWM wave outputted by the controller can be adjusted, the control precision on the angle and the speed of the swing of the light wave probes is higher, and the instantaneity and the accuracy for recognizing the coal gangue mixing degree in the dynamic coal/ rock flow are better.