Organic Light-emitting Diodes (OLEDs) have been extensively researched due to their meaningful advantages in terms of Self-luminous, wide viewing angle and low power as a new display technology. Thus, OLEDs are considered to be one of the next-generation mainstream display technologies and have a higher and higher penetration rate in the display terminal and lighting fields. However, OLEDs still have technical problems such as external quantum efficiency and poor stability, which severely limit the further development of OLEDs. Therefore, improving the light efficiency of OLED devices is the key to its application in the field of lighting and display. In OLED devices, most of the photons generated by the recombination of excitons are captured by the total internal reflection at the interface between the air and the substrate. Therefore, there is still much room for improvement in the light coupling efficiency of OLED devices in terms of increasing energy efficiency. By integrating high-efficiency optical extraction structures the device, improving the light efficiency of OLEDs has become a key concern in this field. The light extraction includes internal light extraction method and external light extraction method. Among them, the external light extraction method can not affect the electrical characteristics of devices, and has the advantages of simple process and low cost. As an external light extraction method, microlens array can improve the light efficiency of the devices. However, the microlens array is a micron-sized structure, and the effect of the light extraction is not excellent enough. In recent years, a nanogratings structure has received extensive attention and research on its fabrication process and light extraction performance because it can change the direction of light and suppress the total reflection. In this paper, A microlens/nanogratings hybrid structure in order to improve the light efficiency of OLED devices is proposed. The main research contents and results are as follows:1) Microlens arrays with the uniform morphology and the controllable size were prepared by photoresist thermal reflow method, and the nanogratings used to improve the light extraction performances were prepared by plasma treatment of oxygen, argon.The influence of plasma surface treatment time, gas flow with argon and oxygen on the morphology of nanograting, the formation mechanism of nanograting as well as the OLED light extraction performances of microlens/nanogratings hybrid structures were studied. The experimental results proved that the formed nanograting was produced based on the stress mismatch of the bilayer film system. The nanograting can be formed on the surface of PDMS by plasma surface treatment after removing the external force due to the formation of a rigid silica-like layer on the surface of PDMS. In addition, the period and amplitude of the nanograting can be adjusted by changing the plasma treatment process conditions.Generally speaking, the period and amplitude of the nanograting obtained by oxygen plasma treatment were much smaller than those obtained by argon plasma treatment.Subsequently, the nanogratings were incorperated into the surface of the microlens arrays and the hybrid structures of the microlens/nanogratings were formed by soft printing technology. 2)The OLED light extraction performance of the microlens arrays and the microlens/nanogratings hybrid structures of different sizes was compared and studied. The test results showed that the introduction of external structures does not affect the electrical characteristics of the green OLED devices. In addition, the microlens array has the best light extraction effect when the height of the microlens was about 19.6 μm. Its external quantum efficiency with OLED devices was increased by about 8.38%. When the height of the microlens was about 19.6 μm, the period of the nanogratings was about 600±50 nm, and the amplitude of the nanogratings was about 20±5 nm, the microlens/nanogratings hybrid structure can be used to effectively improve the external quantum efficiency of green OLED devices, which was 33% higher than that of pure OLED devices. Therefore, the small-size nanogratings fabricated by oxygen plasma can further improve the light extraction performance of microlens arrays for green OLED devices.