This study demonstrates that attaching micro-lens array films (MAFs) on the substrate and reducing the substrate thickness of OLED can significantly increase the power efficiency, while simultaneously reduce image blurring. Using a point source model, based on Monte-Carlo ray-tracing method, the power efficiency enhancement and reduction of blur effect are respectively discussed in three different regions of the MAFs attached substrate: partially reflecting region, transmitting region, and light guiding region of micro-lenses. According to the equations, derived with regard to the substrate thickness and the displacement from the point source and based on geometric relations corresponding to different regions, reducing the substrate thickness will result in different levels of enhancement for power efficiency in different regions. By comparing OLED with MAFs and bare OLED, the overall enhancement ratio of power efficiency is 1.46, which can be further improved to 1.78 by reducing the substrate thickness from 700 μm to 50 μm, and the blurlength is reduced from 942 μm to 255 μm. The simulation results demonstrate the possibility of applying MAFs to OLED for higher power efficiency without image degradation in display and lighting applications.