Switching power supply printed circuit board with low electromagnetic interference

The utility model relates to the technical filed of circuit boards, particularly to a switching power supply printed circuit board with low electromagnetic interference. The structure is that circuit ground wires on the circuit board comprise a first main path, a second main path, a third main path and a fourth main path, wherein the first main path is a path connected between a current detection resistor R16 of a MOSFET switch tube Q1 and an input end filter capacitor C1 through a printed circuit line, the second main path is a path connected between a grounding pad of a transformer and the input end filter capacitor C1 through a jumper wire, the third main path is a path connected among a pad of a diode D6, which is indirectly connected with a feedback end of a PWM chip U1, a grounding pad of an optocoupler PC1 feedback pin and a pad of the input end filter capacitor C1 through a printed circuit line, the fourth main path is a path connected between a grounding pad of a Y capacitor CY2 and the grounding pad