Abstract: In this paper, the limitation of T-Matrix structure is analyzed. It is found that a solution by T-Matrix method can be transformed to a canonical solution when the boundary of the scatterer tends to the cylindrical form and the scatterer is illuminated by E-plane wave. The transition from T-Matrix method to canonical solution is established. It is concluded that T-Matrix is diagonal with the scatter boundary in this limit situation. This is also the limit of numerical solution.