In this article, a physics-based analytical model which considers the channel charge (Qch) for enhancement-mode p-GaN power high-electron-mobility transistors (HEMTs) is developed. First, by considering the same dynamic channel charge (dQch) for the Schottky/ p-GaN junction capacitance (Cj,Sch) and the p-i-njunction capacitance (Cp-i-n), due to the p-GaN/AlGaN junction and two-dimensional electron gas (2DEG) charge, the analytical formula to calculate the voltage drop in the p-GaN layer (VpGaN) is presented. Second, by implementing the analytical formulae in the advanced SPICE model (ASM) GaN model, the proposed physics-based model reliably fits the measured C-V and ID-VG characteristics of the samples under different processing conditions. This provides significant insight regarding the Mg concentration, the voltage drop at the Schottky metal/p-GaN junction (Vj,Sch), and the voltage drop at the p-GaN/AlGaN junction (Vp-i-n). Finally, the ID-VG and ID-VD characteristics of enhancement-mode p-GaN power HEMTs are modeled, displaying good agreement with the experimental data.