Platelet transpiration cooling is one of the key techniques for the developing reusable launch vehicle. The thinner of the platelet, the better effect plate transpiration will gain. Meanwhile, the platelet unit may get wrinkled if thermal stress is large enough. One-dimensional non-equilibrium model is adopted to analyze the heat transfer characteristics of platelet transpiration cooling. The assumption of rectangular plate with three-side simple supported and one-side free is taken and Galerkin method is applied for analyzing the stability of platelet unit. Analysis indicates that as the heat transfer intensity increases, the thermal soaking depth decreases, while more coolant is needed to keep the heated wall at design temperature. Also, the critical thickness for the platelet not to get wrinkled gets larger with the increasing thermal soaking depth.