The present disclosure provides a metal clad laminate, a preparation method thereof, and a method for preparing a flexible circuit board by using the same. The metal clad laminate of the present disclosure includes a first metal foil, a first polyimide layer directly disposed on the first metal foil, a second metal foil, and a second polyimide layer directly disposed on the second metal foil, the first polyimide layer being in contact with the second polyimide layer. The metal clad laminate of the present disclosure is equivalent to a double-sided flexible copper clad laminate (FCCL) in structure, is superior to a single-sided FCCL in terms of mechanical performance in reducing warpage, and has the advantage of being useful for circuit fabrication simultaneously on both sides thereof.