Abstract: In order to improve the drying quality of astragalus, fresh astragalus is processed using hot air vacuum drying technology. Univariate experiments were carried out based on the indicators of color, total flavonoid content and drying time to study the influence of slice thickness, hot air temperature, moisture content at intermediate conversion point and vacuum temperature on the quality of Astragalus. Using Central-Composite response surface method and comprehensive scoring method, a quadratic regression mathematical model was established to analyze and obtain optimized process parameters. The results showed that the primary and secondary effects of various influencing factors on the quality of Astragalus were vacuum temperature> slice thickness> moisture content at intermediate conversion points> hot air temperature. The best process parameters: slice thickness 4.86 mm, hot air temperature 52℃, conversion point moisture content 35%, vacuum temperature 69℃, color difference value of 9.89, total flavonoid content of 0.78 mg/g, drying time of 105 min, comprehensive score of 63.69. The research results can provide a reference for the drying process of astragalus.