Abstract: OBJECTIVE To optimize the extraction process of Guiqi Yiyuan decoction and establish its quality control method. METHODS L₉(3⁴) orthogonal test was used to optimize the extraction process of Guiqi Yiyuan decoction by using index as comprehensive evaluation of the extraction rate, total polysaccharide content and n-butanol extract content. Thin layer chromatography(TLC) was used to identify Astragali Radix, Angelicae Sinensis Radix, Lycii Fructus and Ginseng Radix et Rhizoma in the decoction. The content of glucoside of calycosin as the main active ingredient of Astragali Radix was determined by HPLC. The differences in relative density, insoluble matter and loading amount were checked according to the Chinese Pharmacopoeia 2020 edition, and the quality control method was established. RESULTS The optimum process was 12 times water, 4 h extraction time and 2 times extraction. TLC identification results showed that the chromatograms had clear spots, good separation and strong specificity. The linear range of calycosin glucoside was 0.089 6-1.344 0 µg(r²=0.999 4), the average recovery was 99.51%, RSD was 2.59%(n=9). The relative density of decoction was 1.39, and the difference of insoluble matter and loading amount was in accordance with the provisions of Chinese Pharmacopoeia 2020 edition. CONCLUSION The optimized water extraction process is scientific and reasonable, and the quality standard is effective and controllable, which can be used for the quality control of Guiqi Yiyuan decoction.