<p>By combining the effects of synthetic jet Reynolds number (<i>Re</i>_<i>sj</i>), porous wall porosity (<i>ϕ</i>) and porous wall hole diameter (d_<i>h</i>*), Li et al. (AIAA J 58:722–732, 2020) and Xu et al. (Phys Fluids 33:035140, 2021) presented a dimensionless similarity parameter [(<i>Re</i>_<i>sj</i>²<i>d* </i>_<i>h</i>³)^<i>ϕ</i>] to characterize the interaction between synthetic jet vortex rings and a porous wall. To futher incorporate the jet-exit-to-wall distance (<i>H</i>^*) into this similarity parameter, an experimental study was conducted to inverstigate the effect of the jet-exit-to-wall distance (<i>H</i>^* = 2, 4, 6, and 8) on the impingement of synthetic jet vortex rings onto a porous wall under three Reynolds numbers (<i>Re</i>_<i>sj</i> = 300, 600, and 900). By establishing the relationship between the loss of jet momentum flux and the jet-exit-to-wall distance (<i>H</i>^*) at different <i>Re</i>_<i>sj</i>, a more comprehensive similarity parameter [(<i>Re</i>_<i>sj</i>²<i>d</i>_<i>h</i>^<i>*</i>3<i>H</i>^*−0.64)^<i>ϕ</i>] was derived to characterize this vortex rings-porous wall interaction. Given the substantial impact of <i>H</i>^* on the vortex ring strength upon the impingement, an effective interaction velocity (<i>V</i>_<i>j,eff</i> = <i>V</i>_<i>j</i>/<i>H</i>^*0.32±0.045, <i>V</i>_<i>j</i> is the characteristic velocity of the synthetic jet) was introduced, so that [(<i>Re</i>_<i>sj</i>²<i>d</i>_<i>h</i>^<i>*</i>3<i>H</i>^*−0.64)^<i>ϕ</i>] was transformed as [(<i>Re</i>_<i>eff</i>²<i>d</i>_<i>h</i>^<i>*</i>)^<i>ϕ</i>], where <i>Re</i>_<i>eff</i> was the Reynolds number based on <i>V</i>_<i>j,eff</i>. This new similarity parameter effectively characterized both the losses of the momentum flux and kinetic energy transport due to impinging onto a porous wall in over 50 cases from current and previous experiments, thus verifying its validity at least in the range of [(<i>Re</i>_<i>eff</i>²<i>d</i>_<i>h</i>^<i>*</i>)^<i>ϕ</i>] ≤ 1000.</p>