Transferable microlens-structures were fabricated on the substrate of OLED by using nanoimprint lithography. As a result, the waveguide effect on each organic layer was reduced, which can facilitate the optical coupling of the substrate and is expected to increase luminous efficiency, and finally, the device with high brightness can be fabricated. Firstly, ultraviolet exposure and wet etching technology were combined to fabricate high-precision nanoimprint template with quartz glass; secondly, the cleaning and anti-adhesion treatment were used and finally transferable microlens-structures were fabricated on the substrate of OLED by using hot nanoimprint lithography. The result shows that the lens micro-structures are characterized by good flatness, high nanoimprinting precision. The parameters of micro-structures such as period, diameter and length were optimized using Finite-difference time-domain (FDTD) and finally, the optical crystal micro-structure with the photonic band gap effect was fabricated. The light outcoupling efficiency can be increased effectively due to the photonic band gap effect produced by photonic crystal structures on the substrate of OLED. The measuring result showed that both the emission spectrum and the light intensity were increased.