The invention discloses a device for monitoring an operation speed of a power line type fieldbus belt conveyor, comprising a belt conveyor operation speed detection and treatment device and a dynamic power-supply system connected with the belt conveyor operation speed detection and treatment device, wherein the belt conveyor operation speed detection and treatment device comprises a sensor detection unit and an electric cabinet matched with the sensor detection unit; the electric cabinet comprises a control cabinet body, a signal conditioning circuit connected with the sensor detection unit, a microprogrammed control unit (MCU) processor and an input/output (I/O) communication interface connected with the MCU processor; the sensor detection unit comprises a tape speed sensor and/or rotate speed sensor; and the MCU processor is connected with a main programmable logic controller (PLC) control system through the I/O communication interface and a cable. The device is simple in structure, small in volume and convenient for installation, signal transmission is stable, intelligent level is high, operation and maintenance work load is less; and by using the device, the problems, existing in the current belt conveyor operation speed monitoring device in a thermal power plant, such as fussy wiring, far cable distance, extremely difficult construction and the like, are solved.