Multiple ion beam facilities are powerful tools to simulate the irradiation effects of neutrons on relevant nuclear materials. Since hydrogen and helium are often generated in neutron irradiated materials as transmutation products and they play important roles in the defect evolution, the triple beam accelerator and transmission electron microscope link in situ facility instead of a monobeam or dual-beam facility is necessary to simulate neutron irradiation. A hydrogen-helium dual-beam ion implanter has been developed for a triple ion beam in situ facility at Xiamen University. A Penning ion source has been developed to produce H2 + and He+ simultaneously. A special system consisting of two Wien filters and an Einzel lens has been proposed to purify the species from a single Penning source and allow for the measurement of the He+/H2 + ratio, without disturbing the accelerator settings. The detail of this dual-beam ion implanter will be introduced in detail.