The invention discloses a connection changing circuit of a switching power supply seven-pin chip. The connection changing circuit is characterized in that eight pins of a power supply chip U2 (VIPER12) are disassembled and replaced with seven pins of a power supply chip U1 (FGD200), a high-frequency switching power supply transformer T90 is replaced, the data of the connection changing circuit after replacement is that: a high strength enameled wire 0.19 is wound for 180 T from a first pin to a second pin of a primary winding; a high strength enameled wire 0.51 is wound for 15T from a fifth pin to a sixth pin of a secondary winding, and is wound for 12T from the sixth pin to a seventh pin; and a layer of insulating fish paper is additionally arranged between each level when in winding.