We investigate a sufficient condition for hamilton cycle occurring in balanced bipartite graphs with the neighborhood of vertex set.In this paper,we apply the structure of D_3-cycle and Bipartite Hopping Lemma to show that any 2-connected balanced bipartite graph on 2n vertices is hamiltonian if it satisfies |N(X)| (n + |X| +1)/3 for any XV_i.This theorem is the bipartite graph form of the conclusion that any 2-connected graph on n vertices satisfying |N(X)| (n + |X|-1)/3 for anyΦ ≠X V(G) and the minimum degree δ(G) ≥(n + 2)/3 is...