A　numerical　approach　is　carried　out　to　investigate　the　energy　absorption　efficiency　of　density　graded　aluminium　foam.　Effects　of　blast　load　impact　velocity,　loading　duration　and　sample　thickness　on　the　input　energy　density　and　output　energy　density　of　the　graded　foam　are　investigated.　The　stochastic　meso-scale　aluminium　foam　structure　is　generated　by　adopting　a　2D　Voronoi　technique　and　the　commercial　software　ANSYS/LS-DYNA　is　used　for　the　FE　modelling.　Parametric　study　shows　that　the　density　graded　aluminium　foam　is　effective　in　improving　energy　absorption　capability　while　keeping　a　lower　stress　transmitted　to　the　substrate　or　the　protected　structure　if　it　is　properly　designed.