This paper presents detail on experimental and numerical data for flow control at heat exchanger with bimetal-fin. New type of fin named bimetal-fin was made of magnesium and chromium alloy. Bimetal-fin bends according to the temperature, thus flow can be controlled to enhance or decrease the heat transfer coefficient at the wall of heat exchanger. PIV(Particle Image Velocimetry) test was performed to examine the flow behavior around bimetal-fins according to temperature. CFD(Computational Fluid Dynamics) was used to design the heat exchanger using bimetal-fin. It was researched that the bimetal-fin can confine the fluid near wall by bending effect to decrease the heat transfer coefficient at wall. As a result, the bimetal-fin bends by 40°at 60℃, and the recovered heat increased by 3% for single channel by insulation effect. It was confirmed that the bimetal-fin can be used as an insulation material at heat recovery system.