A SMD transformer structure includes a substrate unit, a magnetic unit, a coil unit and a shielding unit. The substrate unit includes a support substrate. The magnetic unit includes at least one magnetic material core bar disposed on the support substrate. The coil unit includes at least one transformer coil assembly wound around the magnetic material core bar. The transformer coil assembly includes a plurality of transformer coils wound around the magnetic material core bar, and each transformer coil has two opposite end portions respectively and electrically connected to the corresponding first electrode and the corresponding second electrode of the substrate unit. The shielding unit includes at least one magnetic shielding board disposed on the magnetic material core bar. Whereby, the SMD transformer structure not only can be simplified to reduce its size, but also can be automatically manufactured to increase its production efficiency and product yield (reliability).