  We attempt to explain the recent ATLAS 3$\sigma$ excess of dilepton events
with an invariant mass near $Z$ peak through the gluino-mediated sbottom
production in a simplified scenario inspired by the Minimal Supersymmetric
Standard Model (MSSM). The additional $Z$ bosons can be produced through the
cascade decay chain $\tilde{g} \to b \tilde{b}^{\dagger}_{1} \to b \bar{b}
\tilde{\chi}^{0}_{2,3} \to b \bar{b} \tilde{\chi}^{0}_1 Z$, in which $\tilde
b_1$ is the right-handed sbottom, $\tilde\chi_1^0$ is the bino-like lightest
supersymmetric particle (LSP) and $\tilde\chi_{2,3}^0$ are two nearly
degenerate higgsino-like next-to LSPs (NLSPs). Taking into account the
constraint from the LHC search for the gluino-mediated sbottom production in
the final states with the missing transverse energy and at least three
$b$-jets, we find that the ATLAS on-$Z$ excess can only be marginally explained
at $2\sigma$ level. We also note that within the scenario where the gluino
predominantly decays to the right-handed stop instead of the sbottom, the
excess can hardly be explained, since the $Z$-boson is not produced in the stop
dominant decay channel, $\tilde{t}_1 \to b \tilde{\chi}^+_1$.
