Abstract: The longitudinal wall heat conduction, the nonuniformity of temperature field and fluid flow distribution could be coupled and could cause the deterioration of heat exchanger efficiency, especially for the compact heat exchanger. The effect of fluid flow nonuniformity on heat exchanger efficiency is the most important one among the three because it can intensify longitudinal wall heat conduction and the maldistribution of interior temperature. The complicated interior structure and many other factors can cause fluid flow nonuniformity in the plate-fin heat exchanger. The objective of this paper is to investigate the effect of different header configuration on the fluid flow distribution in the plate-fin heat exchanger. It is found that the effect of header configuration on flow maldistribution in the plate-fin heat exchanger is mainly shown in the vertical direction of gross flow passage. To change header configuration can make the flow distribution more uniform in the vertical direction of gross flow passage. Optimized configuration of header can effectively improve the flow distribution in the plate-fin heat exchanger.