The present invention includes an N-type semiconductor layer, an active layer, a P-type semiconductor layer, a metal mirror layer, a protection adhesive layer and a metal buffer layer that are sequentially stacked. The protection adhesive layer is selected from a group consisting of a metal oxide and a metal nitride, fully covers one side of the metal mirror layer away from the P-type semiconductor layer, and includes a plurality of conductive holes. The metal buffer layer penetrates through the conductive holes to be electrically connected to the metal mirror layer. After forming the metal mirror layer on the P-type semiconductor layer, the protection adhesive layer that fully covers the metal mirror layer is directly formed to thoroughly protect the metal mirror layer by using the protection adhesive layer, thereby maintaining a reflection rate of the metal mirror layer and ensuring light emitting efficiency of a light emitting diode.