The invention discloses a high-efficiency light emitting diode based on a nano-wire structure and a preparation method thereof, and mainly solves the problems of a conventional LED that the light emitting efficiency is low because the hole injection efficiency is not high. The high-efficiency light emitting diode includes a c-surface sapphire underlay (1), a high-temperature A1N nucleation layer (2), an n-type GaN layer (3), an A1xGa(1-x)N/A1yGa(1-y)N multi-quantum well (4), a p-type GaN layer (5), and electrodes (6), wherein the multi-quantum well includes five periods, x and y of the A1 content are controlled by flow of a gallium source and an aluminium source so that an LED with different wavelengths is obtained, a metal ball is formed through creep deformation of metal at high temperature and serves as a barrier layer, and nano grooves are etched at even intervals in the quantum well to enable the p-type GaN layer to be inlaid and grow in the nano grooves, so that contact areas between the p-type GaN and the quantum well are increased and hole injection is facilitated. The preparation method enables the light emitting efficiency to be improved and can be used for making ultraviolet and deep ultraviolet light emitting diodes.