The invention provides a frequency tripling transformer, which comprises an iron core and a winding, wherein the iron core comprises a first transverse yoke, a second transverse yoke, a third transverse yoke, a fourth transverse yoke, a first upright post and a second upright post; the first upright post and the second upright post are parallel and opposite; two ends of the first transverse yoke, the second transverse yoke, the third transverse yoke and the fourth transverse yoke are vertically connected to the first upright post and the second upright post respectively; the winding comprises an A-phase winding, a B-phase winding and a C-phase winding; the A-phase winding is wound between the first upright post and the second upright post and is located at the part between the first transverse yoke and the second transverse yoke; the B-phase winding is wound between the first upright post and the second upright post and is located at the part between the second transverse yoke and the third transverse yoke; and the C-phase winding is wound between the first upright post and the second upright post and is located at the part between the third transverse yoke and the fourth transverse yoke. The frequency tripling transformer has the beneficial effects that the cost is saved and the size is reduced.