Abstract: Flow drill screw（FDS） is a new joining technology for lightweight car body.In order to promote the application of FDS technology in lightweight car body, a double motor driven flow drill screw tightening device was designed, and the structure design and analysis of the device were carried out, the mechanical structure was modeled by SolidWorks, and the motion check and finite element analysis were also carried out.The results show that the designed mechanical structure meets the requirements, and the feasibility was verified by the motion check and finite element analysis.It is concluded that the designed tightening device has laid an engineering foundation for the development of flow drill technology.