The specimen of wing lowerpanel attachment is designed without root rib and dihedral angle generally, but these two elements may influence the consequence of the lowerpanel attachment test. This paper sets up three models by CAE（computer aided engineering） in order to evaluate the effect of the root rib and dihedral angle. The analysis results show that stress fringe and load distribution of fasteners has a great difference with the real structure on deformation without the two elements. This paper recommends that it is essential to design the specimen of lowerpanel attachment concerned with the real structure.