Abstract: The flow characteristics of a plate-fin heat exchanger in the wind tunnel were studied. Firstly, the turbulence characteristics and pressure loss of the plate-fin heat exchanger and the finned oval tube heat exchanger were compared, and then the turbulence developments downstream of the heat exchanger under different inflow wind speeds and spoiler angle conditions were studied by experiments. Finally, the impacts of typical structures on the flow disturbance downstream of the heat exchanger were obtained. The results show that the plate-fin heat exchanger has less disturbance to the air flow and much smaller pressure loss under the same heat transfer condition than the finned oval tube heat exchanger. The plate-fin heat exchanger has good rectifying effect, and the flow disturbance, which has little relation with the incoming flow conditions, is mainly determined by its own structures. The disturbance of the large thickness structures in the heat exchanger propagates long distances, and a proper rectifier scheme is needed to reduce the disturbance.