An electronic transformer used in low voltage lamps mainly includes an outer case, an electronic controlling circuit and a voltage switch isolating transformer. Therein, the outer case consists of an upper cover plate (1) and a lower cover plate (2); the electronic controlling circuit and the magnetic core coil (6) of the voltage switch isolating transformer are put between the upper cover plate (1) and the lower cover plate (2); characterized in that the outside of the lower cover plate (2) provides concaving grooves (9) adapting to coil winding, the corresponding line passage holes (10) and a center hole (12) of the lower cover plate; the windings of the voltage switch isolating transformer are embedded in the grooves (9) through the center hole (12) of the lower cover plate, the line passage holes (10) and the center hole of the magnetic core coil (6), the upper cover (1) plate and the lower cover plate (2) are embedded with each other. The electronic transformer in accordance with the invention is portable, thin, beautiful, convenient, with better heat dispersion, and up to the correlative international safety standard.