The invention discloses a carbon fiber cutting device which comprises a working table. The working table is provided with a controller, a driving mechanism and a fixed component, the controller is connected with the driving mechanism, a sliding base is arranged between the driving mechanism and the fixed component, an L-shaped base and a support plate are arranged on the sliding base, a motor is arranged on the L-shaped base, a rotating shaft is arranged on the motor, one end of the rotating shaft penetrates through the support plate, rotary knives are uniformly distributed on the rotating shaft, knife grooves are uniformly distributed in the working table, the knife grooves are located under the rotary knives, and elastic fixed plates are symmetrically distributed on the working table. The carbon fiber cutting device is simple in structure, automatic cutting is achieved, the cutting efficiency is high, the effect of finished products obtained after cutting is good, and the cost is low.