The invention relates to the technical field of aluminum electrolysis, in particular to a cathode carbon block turnover device for an aluminum electrolytic cathode assembly line. A turnover cylinder is fixed on a supporting crossbeam through a supporting roller, the supporting crossbeam is fixedly connected with a pedestal, and a position sensor is arranged at one end of an outlet of the turnovercylinder; a motor bracket is fixedly connected with the middle part of the supporting crossbeam, and a small motor is fixedly connected with the motor bracket through bolts; and a rack is packaged and fixed at the middle part on the external cylindrical surface of the turnover cylinder, and a gear is fixedly connected with the shaft end of the small motor. The turnover device has simple structure, convenient operation and high automation degree of turnover operation; the cathode assembling quality is increased, the operating environment of site operation is improved, the labor intensity of workers is lightened, and the assembling capability and the labor productivity of assembling working procedures are enhanced, thereby prolonging the life of an electrolytic cell. The cathode carbon block turnover device is suitable for cathode assembling production and can be used for assembling cathode carbon blocks in 160kA and 200kA cell types.