Abstract: To investigate the performance of sandwich structure with the V-pattern folded core used for integral thermal protection structure with active cooling, the heat transfer process in the sandwich structures with the folded cores under a constant heat flow loading is simulated by the computational fluid dynamics software Fluent during the forced convection, with analysis of the characteristics of the heat transfer and the flow pattern. The heat transfer performances of two kind of flow channels in the sandwich structure are compared, and an improved scheme of using the flow in the opposite direction of the adjacent flow channel is proposed to improve the utilization rate of the coolant and to make the temperature distribution in the structure more uniform. The active cooling effects of the folded-core sandwich panel and the corrugated-core sandwich panel are compared. Compared with the corrugated sandwich panel of the same geometric parameters, the corrugated sandwich panel enjoys a better heat transfer performance at the cost of a greater equivalent density and the inlet & outlet pressure drop loss. By comparing among several commonly-used thermal efficiency indexes, a new thermal efficiency index is defined with consideration of the heat transfer performance, the pump power and the structure weight. With different thermal efficiency indexes as the objective function, the geometrical parameters of the folded core such as L, W, S are optimized preliminarily.