Abstract: With the continuous developments of display technology, flexible display is considered to be the potential next generation of display techniques due to their excellent properties such as light weight, thin, durability and roll. Implementation of the flexible display is dependent on not only the improvement of the existing manufacturing technology, but also the new design of satisfying materials. As a significant part of flexible display devices, the flexible substrate is crucial to flexible display and have drawn extensive attention, which is concentrated on the research of some essential properties to meet growing demands, such as optical transparency, flexibility, thermal stability, and water vapor and oxygen resistance. At present, five types of substrates are investigated for the flexible display, including polymer, ultra-thin glass, stainless steel, paper and bio-composite. Among these, the first three substrates are commonly used. This review shows recent research progress of available materials for flexible display substrates, and makes a comparison with these materials on optical transparency, thermal resistance, mechanical properties, and water vapor and oxygen resistance. Compared with ultra-thin glass and stainless steel, polymer substrates have advantages in transparency, flexibility, light weight and good durability. Finally, the future research direction of polymer substrate is presented.