A switching power supply, comprising: a constant-current switch circuit, a first single stage PFC circuit, a first transformer, and a constant-current feedback circuit; a constant-voltage switch circuit, a second single stage PFC circuit and a second transformer; the second transformer comprises a primary winding, a secondary winding, and an auxiliary winding disposed at a primary side of the second transformer; an input terminal of the constant-voltage switch circuit is adapted to receive a direct current, an output terminal of the constant-voltage switch circuit is coupled to the primary winding of the second transformer, the auxiliary winding of the second transformer is coupled to a zero current detection terminal of the second single stage PFC circuit, and the secondary winding of the second transformer is electrically couplable to a main board; characterized in that, the constant-current feedback circuit is adapted to sample a current output by the first transformer, and feed back the sampled current to the first single stage PFC circuit; according to the sampled current, the first single stage PFC circuit is adapted to output a first switch signal, drive the constant-current switch circuit to be turned on or off, and control a load current of LED light bars to be constant, wherein an output terminal of the first transformer is connectable to an input terminal of the LED light bars; the second single stage PFC circuit is adapted to output a second switch signal to control the constant-voltage switch circuit to be turned on or off at a zero crossing point of the current in the auxiliary winding of the second transformer detected at the zero current detection terminal of the second single stage PFC circuit; and the second single stage PFC circuit is further adapted to sample a voltage output by the second transformer to obtain a sampled voltage, and regulate a duty ratio of the second switch signal according to the sampled voltage, to regulate the output voltage to the main board to be constant; the switching power supply further comprises a first secondary rectifier and filter circuit and a second secondary rectifier and filter circuit; the first secondary rectifier and filter circuit is configured to rectify and filter a pulsating direct current output by the first transformer; the second secondary rectifier and filter circuit is configured to rectify and filter a pulsating direct current output by the second transformer. a constant-current switch circuit, a first single stage PFC circuit, a first transformer, and a constant-current feedback circuit; a constant-voltage switch circuit, a second single stage PFC circuit and a second transformer; the second transformer comprises a primary winding, a secondary winding, and an auxiliary winding disposed at a primary side of the second transformer; an input terminal of the constant-voltage switch circuit is adapted to receive a direct current, an output terminal of the constant-voltage switch circuit is coupled to the primary winding of the second transformer, the auxiliary winding of the second transformer is coupled to a zero current detection terminal of the second single stage PFC circuit, and the secondary winding of the second transformer is electrically couplable to a main board; characterized in that, the constant-current feedback circuit is adapted to sample a current output by the first transformer, and feed back the sampled current to the first single stage PFC circuit; according to the sampled current, the first single stage PFC circuit is adapted to output a first switch signal, drive the constant-current switch circuit to be turned on or off, and control a load current of LED light bars to be constant, wherein an output terminal of the first transformer is connectable to an input terminal of the LED light bars; the second single stage PFC circuit is adapted to output a second switch signal to control the constant-voltage switch circuit to be turned on or off at a zero crossing point of the current in the auxiliary winding of the second transformer detected at the zero current detection terminal of the second single stage PFC circuit; and the second single stage PFC circuit is further adapted to sample a voltage output by the second transformer to obtain a sampled voltage, and regulate a duty ratio of the second switch signal according to the sampled voltage, to regulate the output voltage to the main board to be constant; the switching power supply further comprises a first secondary rectifier and filter circuit and a second secondary rectifier and filter circuit; the first secondary rectifier and filter circuit is configured to rectify and filter a pulsating direct current output by the first transformer; the second secondary rectifier and filter circuit is configured to rectify and filter a pulsating direct current output by the second transformer.