A multi-stage transmission tensioning device for automobile safety comprises a base group (1), a handle group (2) and a multi-stage transmission group (3); the multi-stage transmission group (3) comprises a transmission shaft (25) for pivoting both with the base of the base group (1) and the handle of the handle group (2), a main rotating shaft (28) used for winding a long strap (31), and a transmission wheel fixed on the transmission shaft (25). A fairly large binding force on the straps ultimately can be achieved from a small force applied to the handle by multiple conversions. Different binding forces in the case of applying the same handle force may be got via the increase or decrease of the transmission stages and the change of the transmission ratio of the transmission at all stages.