A current-limiting protection circuit, comprising: a power supply chip and a current-limiting circuit that is electrically connected to the power supply chip; wherein the power supply chip has an output pin (VOUT) and a feedback pin; the current-limiting circuit comprises: a current sampling resistor, at least one voltage conversion resistor (R3, R4, R5), a first operational amplifier, a triode, a first voltage divider resistor, a second voltage divider resistor, and a diode; the output pin (VOUT) is connected to one end of the current sampling resistor; a negative input end of the first operational amplifier is connected to one end of a first voltage conversion resistor, the other end of the first voltage conversion resistor is connected to the one end of the current sampling resistor; a positive input end of the first operational amplifier is connected to one end of a second voltage conversion resistor, the other end of the second voltage conversion resistor is connected to the other end of the current sampling resistor; an output end of the first operational amplifier is connected to a base of the triode, an emitter of the triode is connected to the negative input end of the first operational amplifier, a collector of the triode is connected to one end of a third voltage conversion resistor, and the other end of the third voltage conversion resistor is grounded; the first voltage divider resistor is connected to the second voltage divider resistor in series, one end of the first voltage divider resistor is connected to the other end of the current sampling resistor, and one end of the second voltage divider resistor is grounded; a positive electrode of the diode is connected to the one end of the third voltage conversion resistor, and a negative electrode of the diode is separately connected to the other end of the second voltage divider resistor and the feedback pin; the power supply chip is specifically configured to: convert an input first voltage (Vin) into a second voltage (Vout), and output the second voltage (Vout) to the current-limiting circuit by using the output pin (VOUT); the current-limiting circuit is specifically configured to: detect a first current that passes through the current sampling resistor; convert the first current into a third voltage by using the voltage conversion resistors (R3, R4, R5), the first operational amplifier, and the triode (Tl); output a first reference voltage by using the first voltage divider resistor and the second voltage divider resistor; and output a feedback voltage to the feedback pin according to the third voltage and the first reference voltage, wherein the outputting a feedback voltage to the feedback pin according to the third voltage and the first reference voltage comprises the following: if the third voltage is greater than a sum of the first reference voltage and a positive break-over voltage of the diode, the feedback voltage is a difference between the third voltage and the positive break-over voltage of the diode; or if the third voltage is less than or equal to a sum of the first reference voltage and a positive break-over voltage of the diode, the feedback voltage is the first reference voltage; and the power supply chip is further configured to: when the feedback voltage is greater than a second reference voltage, reduce the second voltage until the first current reaches a preset value; wherein the second reference voltage is a preset internal voltage of the power supply chip. if the third voltage is greater than a sum of the first reference voltage and a positive break-over voltage of the diode, the feedback voltage is a difference between the third voltage and the positive break-over voltage of the diode; or if the third voltage is less than or equal to a sum of the first reference voltage and a positive break-over voltage of the diode, the feedback voltage is the first reference voltage; and the power supply chip is further configured to: when the feedback voltage is greater than a second reference voltage, reduce the second voltage until the first current reaches a preset value; wherein the second reference voltage is a preset internal voltage of the power supply chip.