Long time well-posdness of Prandtl system with small and analytic initial data

In this paper, we investigate the long time existence and uniqueness of small solution to $d,$ for $d=2,3,$ dimensional Prandtl system with small initial data which is analytic in the horizontal variables. In particular, we prove that $d$ dimensional Prandtl system has a unique solution with the life-span of which is greater than $\e^{-\f43}$ if both the initial data and the value on the boundary of the tangential velocity of the outflow are of size $\e.$ We mention that the tool developed in \cite{Ch04, CGP} to make the analytical type estimates and the special structure of the nonlinear terms to this system play an essential role in the proof of this result.