Synergistically double-sided friction stir welding (SDS–FSW) is a significant variant of friction stir welding (FSW). The problems of large deformation and time-consuming of traditional FSW are greatly suppressed by SDS–FSW. SDS–FSW has prompted considerable scientific and technological interests due to its advantages in welding largesized and thick plates or profiles. At present, the research and application of SDS–FSW are still in the initial development stage, and relevant research results are mainly limited to 6061 aluminum alloy. This paper provides an overview of this new technology, including its development history, technical characteristics, typical research results and application prospects. The aim is to provide a reference for the further development and engineering application of SDS–FSW.