The utility model provides a switching power supply transformer. The switching power supply transformer comprises a magnetic core, the magnetic core comprises a magnetic box with a containing cavity and a magnetic column arranged in the containing cavity, openings are formed in the two sides of the magnetic box respectively, the switching power supply transformer further comprises a coil winding,the coil winding is formed by stacking and winding flat enameled wires on the magnetic column in the radial direction of the magnetic column, and an outer coil of the coil winding is wound on an innercoil of the coil winding; pins are formed at the ends of the coil winding, the pins are led out of the magnetic box through the openings, and the two radial sides of the coil winding extend out of the magnetic box through the two openings. According to the utility model, the flat enameled wire is wound in the magnetic column to form the coil winding, and the outer-turn coil is wound on the inner-turn coil, so that the coil winding extends along the radial direction of the magnetic column, the size is reduced, the coil winding can bear larger current, and heating is reduced; and meanwhile, thetwo sides of the coil winding extend out of the magnetic box, so that the heat dissipation efficiency is improved, and the manufactured switching power supply transformer is relatively small in sizeand can bear relatively large current and power.