In this paper, the concept of second header installation is put forward. The experimental investigation on the effects of the inlet pipe diameter (Phi(1(in))), the first header's diameter of equivalent area (Phi(1(out))) and the second header's diameter of equivalent area (Phi(2(in)) and Phi(2(out))) on the flow maldistribution in plate-fin heat exchanger (PFHE) is performed. The results indicate that the flow distribution in PFHE becomes more uniform when Phi(1(out))/Phi(1(in)) is equal to Phi(2(out))/Phi(2(in)). The correlation of the dimensionless flow maldistribution parameter S and Reynolds number is obtained under different header configurations. The ratio of the maximum flow velocity and the minimum flow velocity drops from 2.08-2.81 to 1.2-1.4 for various Reynolds numbers. The experimental studies prove that the performance of flow distribution in PFHE is effectively improved by the optimum design of the header configuration.