The effect of bi-adhesive on the stress distribution in aluminum alloy weld-bonded single lap joint was investigated using elasto-plastic finite element method (FEM). The results from the numerical analysis show that the influence is evidently to the stress distributed along the mid-bondline, especially to the side of nugget near the low elastic modulus of adhesive as well as at the end of overlap zone. The longitudinal stress Sy, shear stress Sxy and von Mises equivalent stress Seqv increase significantly in the nugget and the adhesive with lower elastic modulus while the peak stress in the adhesive layer near the end of the overlap decreased gradually. The effect of bi-adhesive on the stress distribution in the adherend near the interface is similar to that in the mid-bondline of the adhesive layer. It is suitable to use bi-adhesives to improve the load bearing capacity.