Urbano's Theorem plays an important geometric role in the proof of Willmore conjecture, which states that a non-totally-geodesic closed minimal surface x in S^3 has index at least 5 and it is congruent to the Clifford torus if the index is 5. In this talk we  will provide a generalization of Urbano's Theorem to minimal tori in S^4 by showing that a minimal torus in S^4 has index at least 6 and it is congruent to the Clifford torus if the index is 6.  This is a joint work with Prof. Rob Kusner(UMass Amherst).