We theoretically study the light outcoupling efficiency of top-emitting organic light-emitting diode (OLED) with inverted structure and thin-film encapsulation. Thin-film optics is used to optimize the layer thickness to obtain high transmittance. Dipole mode is used to analyze the light outcoupling efficiency of the top-emitting OLED. Through this process, we can optimize the thin-film thickness with high transmittance and optimize the outcoupling efficiency of OLED. Compared with previous research, the current design method is a novel process.