Let E be a Hermitian vector bundle over a complete Kähler manifold (X, ω), dim C X = n, with a d(bounded) Kähler form ω, d A be a Hermitian connection on E. The goal of this article is to study the L 2 -Hodge theory on the vector bundle E. We extend the results of Gromov's [18] to the Hermitian vector bundle. At last, as an application, we prove a gap result for Yang-Mills connection on the bundle E over X.