  In this article, we study the deformation theory of locally free sheaves and
Hitchin pairs over a nodal curve. As a special case, the infinitesimal
deformation of these objects gives the tangent space of the corresponding
moduli spaces, which can be used to calculate the dimension of the
corresponding moduli space. We show that the deformation of locally free
sheaves and Hitchin pairs over a nodal curve is equivalent to the deformation
of generalized parabolic bundles and generalized parabolic Hitchin pairs over
the normalization of the nodal curve respectively.
