Bai-Hu-Jia-Ren-Shen-Tang Decoction (BHJRSTD) is one of the oldest classic Chinese medicine prescriptions which used in the field of treatment of diabetes. However, to the best of our knowledge, the ingredients of this prescription have not been identified, and there are very few studies on the anti-diabetic mechanism of this prescription. Therefore, BHJRSTD was detected and identified by ultrahigh-performance liquid chromatography coupled with Quadrupole-Exactive Focus Orbitrap MS (UHPLC–Q/Orbitrap/MS/MS). We identified 74 compounds, including flavonoids, alkaloids, chalcones, xanthones, phenols, phenylpropanoids, terpenes, triterpenes, amino acid derivatives, etc. Then, Sprague Dawley rats were fed with a high-fat and high-sugar diet for two months and injected with streptozotocin (STZ) to induce type 2 diabetes (T2DM). The diabetic rats were randomized to given metformin (200 mg kg-1•d-1, n 5 15), BHJRSTD extracts (40 g kg-1•d-1) and BHJRSTD extracts (10 g kg-1•d-1) by gavage for 8 weeks. The results confirmed that BHJRSTD significantly decreased the level of MDA and increased levels of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), it shows that the prescription has significant antioxidant activity in the treatment of T2DM. © 2022 The Author(s)