Polylactic acid (PLA) and thermoplastic starch (TPS) are natural and renewable biodegradable materials. Due to the good mechanical properties of PLA and low cost of TPS, the blending of the two polymers shows high potential. Based on the published literature, first of all, the preparation principles of TPS and plasticizing modification of starch were introduced, and then based on the weak interface bonding between PLA and TPS, the compatibilizing mechanism of PLA/TPS blend and compatibilizing system were summarized. The effects of natural fibers and inorganic nano fillers on the properties of the blend system were discussed. Then, the few studied multilayer structures were introduced, which provided a new research idea for PLA/TPS system. Finally, the potential development and application of PLA/TPS system were prospected.