The utility model relates to a car blet field especially relates to a dististyle pretension assembly. A dististyle pretension assembly, the gaseous subassembly that takes place to and connect and to take place the pretension pipe that subassembly work was served at gas, and set up at the intraductal tensioning means of pretension, and one end and the stay cord that tensioning means is connected toand connect the latch hook on another tip of stay cord, the gaseous subassembly that takes place acts on tensioning means, makes tensioning means in the intraductal axial activity of pretension to act on through the stay cord the latch hook. This dististyle pretension assembly can act on the lower part area body, makes the lower part area show consideration for and closes human abdomen, and cooperation winding ware can let the safety belt conductor and driver that laminates completely, promotes the security performance.