Abstract-A new iterative technique based on the T -matrix approach is proposed for the electromagnetic scattering by dielectric cylinders, in particular cylinders with large aspect ratios. For such cases the conventional T -matrix approach fails. We use hypothetic surfaces to divide a cylinder into a cluster of N identical sub-cylinder, for each the T matrix can be directly calculated. Since any two neighboring subcylinder are touching via the division interface, the conventional multiscatterer equation method is not directly applicable. The coupling among sub-cylinder and boundary conditions at the interfaces are taken care of in our approach. The validity of the proposed method is demonstrated through agreement between theoretical predictions and numerical simulations as well as measurements for scattering from dielectric circular cylinders with finite length. The results clearly demonstrate that the new iterative technique can extend regular Tmatrix approach to solve cylindrical cases with large aspect ratio.