Abstract: The variation of the ballistic absorption energy of Dyneema UD66 fiber composite,an ultra-high molecular polyethylene fiber reinforced composite,with molding pressure,areal density and projectile velocity is studied.The molding pressure of UD66 fiber composite has direct effects on the ballistic absorption energy,so the relation of molding pressure with the adhesive bonding force between layers,the thickness of the laminates and density is investigated during the optimum of the molding parameters.The result shows that when the molding pressure is about 2.5MPa,the ballistic absorption energy is up to the highest value.For the study of the principles of the ballistic absorption energy,the deformation and fracture area of the UD66 fiber composite armors after ballistic impact are analyzed.The study results would be valuable for the optimum design.