We perform an analysis of the $D^+ to K^0_S pi^+ pi^0$ Dalitz plot using a data set of 2.92 fb$^{-1}$ of $e^+e^-$ collisions at the $psi(3770)$ mass accumulated by the BESIII Experiment, in which 166694 candidate events are selected with a background
of 15.1%. The Dalitz plot is found to be well-represented by a combination of six quasi-two-body decay channels ($K^0_Srho^+$, $K^0_Srho(1450)^+$, $overline{K}^{*0}pi^+$, $overline{K}_0(1430)^0pi^+$, $overline{K}(1680)^0pi^+$, $overline{kappa}^0pi^+$) plus a small non-resonant component. Using the fit fractions from this analysis, partial branching ratios are updated with higher precision than previous measurements.
