The invention discloses a method for preparing a gallium nitride (GaN)-based photonic crystal light-emitting diode (LED) based on nanoimprint lithography. The method comprises the following steps of: epitaxially growing an N-GaN layer, a multi-quantum well active region and a P-GaN layer on a sapphire substrate in turn, and forming a GaN-based LED epitaxial structure piece; (2) performing anti-sticking treatment on a hard template for nanoimprint; (3) preparing a software template with a complementary pattern of the hard template; (4) respectively evaporating a mask layer and a nanoimprint ultraviolet adhesive layer on the epitaxial structure piece; (5) performing ultraviolet imprint on an evaporated device, and demolding to form a pattern piece with photonic crystals; and (6) etching thepattern and performing subsequent treatment to obtain the photonic crystal LED. In the method, the nanoimprint ultraviolet adhesive layer and the evaporated mask layer are combined to serve as a mask, so that the problem of imprinting difficulties caused by the unevenness of the surface of the GaN epitaxial piece is solved; therefore, the effective hole depths of the photonic crystal are greater.