The productivity of the phenylpropanoid biosynthesis pathway in plants varies depending on the type of stress. In this work, we looked into how different phenylpropanoid chemicals accumulated in Euonymus alatus following exposure to different concentrations of CuCl2 (0.1, 0.5, and 1 mM), HgCl2 (0.1, 0.5, and 1 mM), and NiSO4 (10, 50, and 100 mM). We analyzed some of the individual phenolic chemicals by high-performance liquid chromatography (HPLC). In nearly all cases, rutin showed the largest concentration among the phenylpropanoid chemicals, followed by epicatechin, sinapic acid, p-coumaric acid, trans-cinnamic acid, ferulic acid, and caffeic acid. However, due to the change in the concentration of the heavy metals, the amount of phenylpropanoid changed. The highest accumulation of phenylpropanoid was documented in 0.1 mM CuCl2, whereas it was reduced in 1 mM HgCl2 exposed plants. These findings unequivocally demonstrate that the phenylpropanoid metabolic pathway took part in the heavy metal tolerance process, which shielded E. alatus from the oxidative damage brought on by heavy metals. Thus, under a variety of environmental stress situations, this species with a high tolerance to heavy metals may survive.