An anti-slip safety tensioning device for automobile, comprises a driving handle assembly, an eccentric shaft, a support assembly, a long band and a short band; wherein, the driving handle assembly is located between a pair of support lateral plates of the support assembly, and can be rotatable relative to the eccentric shaft; and when the driving handle assembly is folded, the eccentric shaft is located on a rear side of the top shaft and the eccentric bulge of the eccentric shaft faces the top shaft; the long band having a free end wrapped around the eccentric shaft, and the free end passes through the gap between the eccentric shaft and the top shaft. When in unfolded state, there is a largest gap between the top shaft and the eccentric shaft.