Top-Charm Associated Production at High Energy e^+e^- Colliders in Standard Model

The flavor changing neutral current tcV (V=\gamma,Z) couplings in the production vertex for the process $e^+e^-\to t\bar c$ or $\bar t c$ in the standard model are investigated. The precise calculations keeping all quark masses non-zero are carried out. The total production cross section is found to be $1.84 \times 10^{-9}$ fb at $\sqrt s =200 GeV$ and $0.572 \times 10^{-9}$ fb at $\sqrt s =500 GeV$ respectively. The result is much smaller than that given in ref. \cite{clwy} by a factor of $10^{-5}$.