He and H can be produced by nuclear reaction. In addition, energetic particles of He and T and D, which are isotopes of H, in the plasma of fusion reactor induce the damage in the surface of materials, such as erosion, sputtering and blistering. To investigate the interaction of He and D, amorphous and crystalline FeBSi alloys were irradiated by He or D2 or He+D2 ions with 5 keV. The results of thermal desorption indicated that more He atoms were trapped in both amorphous and crystalline alloy irradiated by He ions than D atoms in those alloy irradiated by D2 ions. Although He and D atoms were trapped FeBSi alloy irradiated by He+D2 ions, desorption peaks of D2 and He were separate. Absorption of D in amorphous alloy was influenced by the presence of He, however, absorption of He was independent of D2 irradiation in both alloys.