A resonant transformer and resonant converter are disclosed. The resonant transformer includes a first bobbin, a first primary winding coil, plural first secondary winding coils, a second bobbin, a second primary winding coil, plural second secondary winding coils and a magnetic core assembly. The first bobbin includes a first winding section and plural single-trough second winding sections. Plural pins are arranged at the first winding section. The first primary winding coil is wound around the first winding section and connected with the pins. The first secondary winding coils are wound around respective single-trough second winding sections. The second bobbin includes a third winding section and plural single-trough fourth winding sections. The second primary winding coil are wound around the third winding section and connected with the pins at the first winding section of the first bobbin. The second secondary winding coils are wound around respective single-trough fourth winding sections.