Shennong's Classic of Materia Medica（Shen Nong Ben Cao Jing) records that dried Rehmanniae Radix “expels blood impediment”，Paeoniae Radix Alba “eliminates blood impediment”，Euodiae Fructus “dispels dampness and blood impediment”，and Magnoliae Officinalis Cortex treats “qi and blood impediment”.The condition of blood impediment involves the blood aspect，with the pathogenesis being impediment，and the essence of the condition being obstruction.This article analyzed the four drugs used to treat blood impediment，referred to as the “four drugs for treating blood impediment”，and reviewed their applications in the Treatise on Cold Damage and Miscellaneous Diseases（Shang Han Za Bing Lun).It is found that dried Rehmanniae Radix cools the blood，dispels stasis，and unblocks impediments，making it suitable for treating chronic internal injury-induced blood impediment，blood impediment in women related to childbirth，and blood impediment caused by external trauma.Paeoniae Radix Alba breaks yin，regulates the nutrient aspect，and unblocks impediments，removing pathogenic factors from the nutrient aspect，and is used for blood impediment caused by blockages in the nutrient qi and yin.Euodiae Fructus disperses cold，eliminates dampness，and unblocks impediments，and is effective for treating dampness-blood impediment caused by cold coagulation and dampness stagnation in the liver.Magnoliae Officinalis Cortex harmonizes Yangming qi and blood，treating qi and blood impediment in the Yangming meridian.Adhering to the concept of integrating medicine and pharmacology，this article deepened the understanding of “blood impediment”，expanded the practical value and clinical application of the “four drugs for treating blood impediment” as recorded in the Shennong's Classic of Materia Medica，and aimed to continually enrich the pathogenesis of impediment-induced atrophy-flaccidity disease and the therapeutic methods，formulas，and theoretical concepts for unblocking impediments to treat atrophy.