The industrialization of organic light-emitting devices (OLEDs) in the field of lighting still faces the challenge of high costs, while solution-processed OLEDs can dramatically reduce their manufacturing cost. However, compared with thermally evaporated OLEDs, solution-processed OLEDs encounter difficulty in building multilayer systems. As the relevant reviews on solution-processed OLED from the perspective of material engineering have been proposed, this paper will mainly summarize multilayer structures of solution-processed OLED from the aspects of device physics and preparation processes. First, we will analyze the necessity of each functional layer based on the carrier/exciton dynamics and optical physics. Next, we will introduce the commonly used solution-processing techniques and discuss the problems involved in the preparation of multilayer films. Finally, we will present the future prospects of solution-processed OLEDs.