The present invention discloses a stacked dual MOSFET package structure and a preparation method thereof. The stacked dual MOSFET package structure comprises a lead frame unit having a die paddle, a first lead and a second lead; a first chip flipped and attached on a top surface of a main paddle of the die paddle; a second chip attached on a bottom surface of the main paddle; and a metal clip mounted on the back of the flipped first chip and electrically connecting an electrode at the back of the first chip to the first lead. A top surface of a metal bump arranged on each electrode at the front of the second chip, a bottom surface of the die pin of the die paddle, a bottom surface of a lead pin of the second lead, and a bottom surface of the first lead are located on the same plane.