As a novel method of realizing current quantization in electric metrology, the technique based on electron accelerators has attracted concentrations recently, because it is feasible to count electron bunches rather than single electrons. As the two critical issues, stable emission and transmission of the electron beams are of importance to promote the application of the accelerator techniques in the current quantization. Based on comprehensive reviews on an existing electron source containing system introduction and emission experiment, a current tuning device with a magnetic element is introduced in this context. By using electromagnetic simulations and beam dynamics calculations, the structures of the entire facility are designed and fabricated. According to the simulations and corresponding analysis, the device can be used to validate the method of current quantization via electron accelerators, and further verification experiments will be conducted in the near future.