Abstract
A new real time formalism, based on the closed-time-path Green's function theory (CTPGF), is employed to obtain Ward-Takahashi identities of QED at finite temperature. It is shown that WT identity in coordinate space is of the same covariant form as that in vacuum field theory. A perturbative check is provided to show that in momentum space, Takahashi's identities hold only in a weak sense.