A method for manufacturing GaN-based film LED based on masklessly transferring photonic crystal structure is disclosed. Two dimensional photonic crystals are formed on a sapphire substrate. Lattice quality of GaN-based epitaxy on the sapphire substrate is improved, and the internal quantum efficiency of GaN-based LED epitaxy is increased. After the GaN-based film is transferred onto heat sink substrate, the two dimensional photonic crystals structure is masklessly transferred onto the light exiting surface of the GaN-based film by using different etching rates between the GaN material and the SiO2 mask, so that light extraction efficiency of the GaN-based LED is improved. That is, the GaN-based film LED according to the invention has a relatively high illumination efficiency and heat sink.