The invention discloses a conveyor belt breakage prevention device of a belt conveyor. The conveyor belt breakage prevention device is mainly composed of a carrier roller supporting system, a capturing system, a belt breakage detection system and a control system. The conveyor belt breakage prevention device of the belt conveyor is characterized in that the capturing system is mainly composed of a center carrier roller mechanism, an upper brake block mechanism, a lower brake block, a motor driving system and a supporting mechanism. The supporting mechanism is composed of a base, a center carrier roller support, a support, a guiding supporting frame and an upper supporting frame. The upper brake block mechanism is mainly composed of an electromagnet, a round guide rail, an upper brake block, an upper brake block sleeve and a guiding sleeve. The motor driving system is mainly composed of a motor, a coupler and a bidirectional threaded screw rod. The belt breakage detection system is mainly composed of an adjusting bolt, a detection device supporting block, a strong spring, a rear sliding block, a front sliding block, a bearing support, a roller shaft, a bearing and a trapezoid guide rail. The control system comprises a PLC, a belt breakage signal detection proximity switch, an upper brake block proximity switch, a lower brake block proximity switch, an upper brake block stroke switch, an upper brake block sleeve stroke switch, a motor driver and an electromagnet driver.