  Based on an $e^{+}e^{-}$ collision data sample corresponding to an integrated
luminosity of 2.93 $\mathrm{fb}^{-1}$ collected with the BESIII detector at
$\sqrt{s}=3.773 \mathrm{GeV}$, the first amplitude analysis of the singly
Cabibbo-suppressed decay $D^{+}\to K^+ K_S^0 \pi^0$ is performed. From the
amplitude analysis, the $K^*(892)^+ K_S^0$ component is found to be dominant
with a fraction of $(57.1\pm2.6\pm4.2)\%$, where the first uncertainty is
statistical and the second systematic. In combination with the absolute
branching fraction $\mathcal{B}(D^+\to K^+ K_S^0 \pi^0)$ measured by BESIII, we
obtain $\mathcal{B}(D^+\to K^*(892)^+
K_S^0)=(8.69\pm0.40\pm0.64\pm0.51)\times10^{-3}$, where the third uncertainty
is due to the branching fraction $\mathcal{B}(D^+\to K^+ K_S^0 \pi^0)$. The
precision of this result is significantly improved compared to the previous
measurement.
