Energy absorption characteristic of energy absorber on the thin-wall metal tube’s plastic deformation under quasi-static loading are studied by test method. Three kinds of evaluation methods are put forward, which can be used to evaluate the cushion properties of energy absorber comprehensively. Based on the analysis of deformation mechanism of energy absorber on the thin-wall metal tube’s plastic deformation, it is obtained that the energy absorber’s ideal energy absorption efficiency can be improved, and load fluctuation can be reduced through pre-processing expansion ring of the energy absorber. At last, energy absorption characteristic of the 12 types of energy absorber, which are pre-processed under, are studied by experiments, and the results show that, the pre-processed energy absorber can greatly increase the ideal energy absorption efficiency.