The multi-channels plate heat exchangers are recommended to be used in the high-efficiency power and propulsion systems. The present study analyzes the large fluid flow maldistribution occurring at the inlet manifold configurations of a high temperature heat exchanger with CFD (computational fluid dynamics) method. Four modified inlet manifolds are proposed, including inclined baffle, segmental baffle, helical baffle and improved helical baffle. It turns out that all the proposed designs have more or less improvement of uniform flow distribution among each channel. By comparing the flow nonuniformity, the Nusselt number and the friction factor, the inlet manifold with equidifferent helical baffles is the best, whose flow nonuniformity can be decreased by 52% averagely. Comparing with the baseline design, meanwhile, the optimal modified design which inducts the spiral fluid flow has effect on the comprehensive performance. The Nusselt number can be increased by 24% averagely due to the produced spiral fluid flow while the pressure drop is in an acceptable range. Furthermore, the corresponding correlation of Nu and f are obtained according to CFD results. (C) 2014 Elsevier Ltd. All rights reserved.