  The k_T-factorization has been widely used for exclusive decays of B-mesons.
In this factorization the pertubative coefficients are extracted from
scattering of off-shell partons. Because the off-shellness of partons the
extracted pertubative coefficients in general are not gauge-invariant. We show
that these perturbative coefficients contain gauge-dependent singularities
beyond tree-level. This leads to that the k_T-factorization is gauge-dependent
and violated in the general covariant gauge. This is not consistent with
expectations of physics. In the factorization there exist two different wave
functions for a B-meson in general. We show that the two wave functions satisfy
different evolution equations whose solutions are used to re-sum large log's.
Based on this fact, the rseummation of large log's at leading log approximation
in the widely used k_T-factorization with only one wave function is
inconsistent.
