A ball cage coupler with an electromagnetic brake is used for the occasions of mechanical equipment, special vehicles and the like. The ball cage coupler comprises a driving shaft, a driving shaft flange, a middle shaft, a driving end outer ring, a driven end outer ring, a steel ball, a holder, a sealing system, a driven shaft flange and a driven shaft. The electromagnetic brake is mounted on the outer diameter of a steel pipe of the middle shaft. A rotor is mounted on the outer diameter of the steel pipe of the middle shaft, and a stator is mounted in an inner hole of the electromagnetic brake. A wire, a switch and a resistor form a closed loop. The rotor rotates with the middle shaft to cut the stator so as to generate the voltage and an electric current. The electric current passes through the closed loop formed by the wire, the switch and the resistor so as to convert mechanical energy into electric energy. A brake alarm and a brake indicator lamp are connected into the closed loop in series and connected in parallel. According to the ball cage coupler with the electromagnetic brake, the structure is compact, power is transmitted, braking can also be achieved, the braking efficiency is high, design and layout of the equipment and the vehicles can be simplified, safety is improved, environment protection is more facilitated, and the ball cage coupler is suitable for the occasions of frequent starting.