Effect of intermediate heat treatment on the microstructure evolution and mechanical properties of A3003/A4343 clad sheet manufactured through new processes were investigated. Raw materials — both A3003 and A4343 alloys — were fabricated by twin roll strip casting process, and then cold rolling and roll bonding were performed with final thickness of 215 µm. In the manufactured clad sheets, the thickness of 3003 alloy was found to be 191 µm, and that of 4343 alloy, 24 µm. Rolled and recovered microstructures appeared at low heat treatment temperatures (260°C, 280°C), and recrystallization/grain growth were noted from the A3003/A4343 interfaces at 573 K or higher temperatures, with the area (recrystallization/grain growth) gradually increasing as heat treatment temperatures increased further. According to the results of tensile tests, yield strength was 223.7 MPa, and tensile strength was 270 MPa in as-rolled state. As the intermediate heat treatment temperature increased, strengths continuously decreased, whereas elongation exhibited an increasing tendency. Until the final tensile fracture, 3003 alloy and 4343 alloy were not separated but maintained well in bonded state. Based on the results of microstructure evolution by which microstructures were divided into three areas and changed following intermediate heat treatment, the tensile properties of A3003/A4343 clad sheets were analyzed and discussed.