According to the laser conditions of the ninth beam of Shenguang-Ⅱ facility,the characteristics of the laser-driving shockwave propagation in Al-Au impedance-matching target were studied by JB code and multi-step technique,respectively.The experimental results were consistent with the numerical simulation results.The results show that the shockwave's maximum stable propagation distance in gold decreases rapidly when shock front propagates from aluminum to gold.Therefore,when people design the Al-Au impedance-matching target, they should first select the Au step thickness, in which the shockwave should propagate steadily. The Al step thickness will be selected according to the calculated shockwave velocity raio of the two materials in impedance-matching target. For the ninth beam of Shenguang-II facility, the suitable Al substrate thickness is about 30 μm, the Au step thickness and the Al step thickness should be selected as less than 10 μm and 17 μm, respectively.