Overcurrent protection circuit and method in switching power supply direct current circuit

The invention discloses an overcurrent protection circuit and method in a switching power supply DC circuit, and the circuit comprises a switching power supply AC-to-DC part and a thermistor RT, and the switching power supply AC-to-DC part is connected with a load through the thermistor RT, and is used for supplying power to the load. The circuit further comprises a silicon controlled rectifier VT and a control circuit, wherein the silicon controlled rectifier is connected in series in a loop between the alternating current-to-direct current part of the switching power supply and the load; the control end G of the silicon controlled rectifier is connected with the control circuit; and the control circuit is used for outputting a control signal to the control end G of the silicon controlled rectifier. The over-current protection circuit has the advantages that the power supply loop is automatically disconnected after the current is over-current, so that the over-current automatic protection is realized; and th