The invention provides a strong current generator with reel iron cores. The strong current generator comprises a base, a housing and iron cores, wherein the housing is arranged on the base; center holes are reserved in the middle of the housing; the iron cores are concentrically arranged in the housing, and are circular reel iron cores of which the inner diameters are greater than 1mm; the outer edges of the reel iron cores are wound by epoxy cotton tapes along the direction vertical to the circumference; the outer edges of the epoxy cotton tapes are evenly wound by primary windings in a grounding manner along the direction vertical to the circumferences of the reel iron cores; one side of the lower part of the housing is provided with an input sleeve and an output sleeve, which are respectively connected with two ends of the primary windings; the reel iron cores are wound by strip-like silicon steel sheets along the circumference direction. According to the technical scheme provided by the invention, transverse and longitudinal joints of the traditional iron core are removed; magnetic resistance and loss are reduced; the noise is greatly lowered; the strong current generator has good impact voltage wave distribution and enough short circuit withstand capability, is large in window size, and can be applied to full-voltage and full-current composite tests of ultra-high voltage equipment, especially ultra-high voltage GIS (geographic information system) equipment, sleeves and the like.