Abstract: To address the issue of the poor germination uniformity, low plug-seedling quality and poor seedling size uniformity of P. exaltatus the effects of single priming agents, namely KCl（0.50%, 0.75%, 1%）, KNO₃（0.50%, 0.75%, 1%）, PEG-6000（5%, 10%, 15%）, and GA₃（100, 200, 300 mg·L⁻¹）on seed germination were evaluated. Subsequently, different combinations of a composite priming agent（PEG-6000 + KNO₃）were examined, and the selected composite was tested on different P. exaltatus cultivars for germination performance and seedling quality traits such as plant height and crown width. The results showed that among the single priming treatments, 10% PEG-6000 or 0.75% KNO₃ produced the best overall germination performance for the cultivar Joey. The composite priming treatment 10% PEG-6000 + 0.75% KNO₃ was significantly superior to all single-agent and control treatments, achieving the highest germination rate（96.13%）and germination potential（88.90%）, increases of 9.15% and 28.04% over the control, respectively. When this composite priming treatment was applied to two cultivars, Matilda and Joey, it not only improved germination rate and germination potential but also markedly enhanced seedling quality. The optimized composite priming agent identified in this study provides a practical tool for improving seed germination and plug-seedling production in P. Exaltatus.