A chip on film package is disclosed, including a flexible film, a patterned circuit layer, a chip, and a dummy metal layer. The flexible film includes a first surface and a second surface opposite to the first surface. The patterned circuit layer is disposed on the first surface. The chip is mounted on the first surface and electrically connected to the patterned circuit layer. The dummy metal layer covers the second surface capable of dissipating heat of the chip. The dummy metal layer is electrically insulated from the patterned circuit layer.