Abstract: Studies the hypervelocity launch feature of graded-impedance flier-plates. Using LS-DYNA, the hypervelocity launch process with graded-impedance flier-plate impacting the secondary flier-plates is numerically simulated, the pressure profiles and velocity profiles of the secondary flier-plates are calculated. The results show that the secondary flier-plate impacted by graded-impedance flier-plate encapsulated with Lexan can be accelerated to a final launching velocity which is 1.63 times larger than the initial impact velocity,and the graded-impedance flier-plate used can generate a quasi-isentropic loading process while it impacts on the secondary flier-plates.