The total flavonoid content of the aerial part of Caryopteris mongolica was determined, the content of some flavonoids was determined, and the microstructural characteristics of the leaf were revealed. C. mongolica has been cultivated at the plantation biostation of the New Medical University in Kherlenbayan-Ulaan, Delgerkhaan soum, Khentii province since 2013. This study was conducted to compare the content of certain phenolic compounds in wild-grown and cultivated C. mongolica. The content of some flavonoids was determined using HPLC, and the total flavonoid content was determined by spectrophotometry. Moisture was determined by the Pharmacopoeia method, and the microstructure study was conducted using Novel light microscopy. Linear regression analysis was employed for the quantitative determination of rutin, luteolin, apigenin, and acacetin content. A one-way ANOVA was applied to compare the total flavonoid and moisture contents between wild-grown and cultivated samples. Analyses were performed using SPSS Statistics 26.0 software. Although there were no statistically significant differences in total flavonoid or moisture content between wild-grown and cultivated C. mongolica plants growing in Mongolia, the cultivated plants exhibited higher levels of some flavonoids. The average contents of rutin, luteolin, apigenin, and acacetin in the wild-grown C. mongolica sample were 0.00471 mg/g, 0.11999 mg/g, 0.11468 mg/g, and 0.06831 mg/g, respectively. In contrast, the corresponding values in the cultivated C. mongolica sample were 0.02371 mg/g, 0.09971 mg/g, 0.35149 mg/g, and 0.32529 mg/g. The total flavonoid content in the aerial parts of wild-grown and cultivated C. mongolica was measured at 0.328±0.049% and 0.310±0.027%, with no significant difference (p=0.350). The moisture content was also not significantly different between the wild-grown (6.78±0.03%) and cultivated (6.88±0.59%), respectively. A comparative anatomical study of the leaves of C. mongolica revealed that the leaves have an isolateral structure, multicellular hairs, and well-developed palisade tissues arranged in multiple layers.