Abstract: Supersaturated drug delivery systems (SDDS) are defined as systems that are able to generate and maintain a sustained drug supersaturation in the gastrointestinal tract, facilitating the oral absorption of drugs with poor water solubility. Supersaturated drug solution is generated from a higher energy form of the drug or rapid dissolution through various formulation options. However, supersaturated solution is a thermodynamically unstable system that can easily lead to drug precipitation, missing the aim of improving the absorption. Therefore, maintenance of the supersaturated state is essential for the development of SDDS. Polymer-based SDDS take polymers as the precipitation inhibitor,which can effectively prevent the precipitation of drugs, generating an excellent effect on maintenance of the stability of supersaturated solution. However, different polymers have distinct anti-precipitation ability, and the mechanisms of such activity supported by the polymer remain unrevealed. In this review, we summarize the research advances in the absorption-enhancing mechanisms and in vitro evaluations of polymers-based SDDS. This review provides a reference for the design of rational SDDS.