  We estimate two-photon exchange contribution to the process $e^+ +e^- \to p +
\bar{p}$. The two-photon exchange corrections to double spin polarization
observables and form factors in the time-like region are calculated. The
corrections are found to be small in magnitude, but with a strong angular
dependence at fixed momentum transfer. These two features are the same as those
in the space-like region. In the view of experiment, the double spin
polarization observable $P_z$ deserves to be considered.
