A light emitting diode (LED) substrate includes a sapphire substrate which is characterized by having a surface consisting of irregular hexagonal pyramid structures, wherein a pitch of the irregular hexagonal pyramid structure is less than 10 μm. A symmetrical cross-sectional plane of each of the irregular hexagonal pyramid structures has a first base angle and a second base angle, wherein the second base angle is larger than the first base angle, and the second base angle is 50° to 70°. This LED substrate has high light-emitting efficiency.