Transformer

The invention provides a transformer. The transformer comprises a coil holder body, a coil holder cover, a metal block and two opposite iron cores, a first through hole is formed in the center of the coil holder body, wire grooves are formed in the periphery of the first through hole, two opposite wire holders are arranged at two ends of the first through hole, a second through hole corresponding to the first through hole is formed in the center of the coil holder cover, a third through hole parallel to the first through hole is formed in the center of the metal block and covers the peripheries of the wire grooves, one end of the metal block extends along the direction vertical to the third through hole to form two folding portions which are parallel to each other, a main core portion inserted into the first through hole is arranged in the center of each iron core, two opposite side portions are arranged on two sides of each main iron core, accommodating grooves for accommodating the coil holder body are form