An efficient signal integrity verification method of coupled interconnect lines is presented. Two coupled lines are decoupled into isolated eigen modes. Then, bit blocks for coupled lines which are composed of the finite size of bits are represented with the fundamental modes. In addition, the crosstalk effects within the bit block are taken into account. Thereby, the crucial input bit patterns for the worst case eye-diagram determination are mathematically modeled, followed by analytical eye-diagram determination. It is shown that not only the proposed technique has excellent agreement with SPICE W-model-based simulation but also is it very computation-time-efficient, compared with SPICE simulation.