An important feature for light ions with low energy is that their transport behaviour might be determined by a simple parameter, We have found that the ion scaled transport cross section a, is such a parameter. The one to one corresponde-ace between a, and ion transport behaviour reflects the inherent similarity among some ion target-energy combination. In the present paper, the definition of the scaled transport cross section is given, and the theoreilcal basis of the scaled parameter determining ion transport behaviour is formulated. Furthermore, the interesting fea-ture has been checked and verified by our numerous transport calculations. Two empirical formulae for particle reflection coefficient and average projected range are given, in which the scaled transport cross section is taken as argument.