A layout of a switching power converter, wherein the switching power converter includes: a capacitor unit receiving or outputting DC voltage; six power transistor units transforming the DC voltage to the AC voltage or the AC voltage to the DC voltage; and a carrier board with the capacitor unit and the six power transistor units on. The layout of the switching power converter includes a first commutation loop and a second commutation loop, in which the six power transistor units are arranged on the same surface of the carrier board. In order to ensure the first commutation loop and the second commutation loop as short as possible, the fifth power transistor unit is located at a middle position of the carrier board, surrounded by the other five power transistor units as closely as possible.