An unequal diameter twin roll caster which can cast clad strips was devised and assembled. The casting of the clad strip was tried, and fabrication of the clad strip was attained. This twin roll caster was planned for the process saving. The clad strip was assembled directly from AA3003 molten metal and AA4045 molten metal at speed of 20m/min. The Si-diffusion-area between the strips was very narrow, and the interface between the strips was clear. The strips were bonded firmly. The strips were not pealed by the cold rolling and the continuous bending.