A control and protection circuit of a control and protection switching device pertains to the technical field of electric industry. The invention includes a signal sampling circuit, a short-circuit detection circuit, a microprocessor circuit, a magnetic flux converter control circuit and a power converting circuit; the signal sampling circuit sends a current signal to the microprocessor circuit after the amplification and the potential uplifting, the short-circuit detection circuit sends a large range signal in the signal sampling circuit to the microprocessor circuit after the processing, themicroprocessor circuit judges whether the short-circuit fault is existed or not, a corresponding control signal is given out and sent to the magnetic flux converter control circuit, the magnetic fluxconverter control circuit converts the low-level signal which is emitted by the microprocessor circuit to a high-level signal by photoelectric isolation, a magnetic flux converter is driven, the power conversion circuit converts the alternating current high voltage to the direct current low voltage, so as to provide the power for the circuits. The circuit transfer method is simple, the structureis simple, the reliability of the actions is good, the anti-interference capacity is strong, and the invention has the advantages of small size and high reliability when the invention is used for thecontrol and protection switching device.