Similar to Mn+1AXn (MAX, M: transition metal, A: A group element, X: C or N, n=1~3) phase materials, MAB (M: transition metal, A: A group element, B: B) phases also exhibit excellent comprehensive mechanical and thermal properties that are applicable to future nuclear reactors. The origination and growth conditions of He bubbles under irradiation in MAB phase MoAlB and Fe2AlB2 have been calculated through first-principles theory in this work. In general, Fe2AlB2 may present lower single/double vacancy formation energies and a consequent higher He bubble number density. The final He bubble shape and comparative average size of MoAlB and Fe2AlB2 have been predicted as well. In MoAlB there will form large platelet-like He bubbles and small spherical ones. In Fe2AlB2 there will form spherical He bubbles with different sizes. These He bubbles can all further link via interlayer vacancies into string-like shape. Fe2AlB2 also possesses higher He-induced embrittlement tendency than MoAlB.