Objective:To determine the active components alignments（ACA） of four flavonoids in hollow root of Baikal Skullcap（hollow root of Scutellaria baicalensis）

so as to provide scientific basis for the establishment of quality standard in accordance with its therapeutic.Method:The ACA were determined by reversed phase high-performance liquid chromatography（RP-HPLC） & herb-herb compatibility.Result:The content of Baicalin-Baica-lein-Wogonoside-Wogonin in four formulas of hollow root of Baikal Skullcap was（75.83 ± 7.25）

（2.72 ± 0.53）

（18.62 ± 2.89）

（1.44 ± 0.37） mg.g-1.Conclusion:The ACA ratio of flavonoids in hollow root of Baikal Skull-cap was 52.44∶ 1.89∶ 12.88∶ 1

with the action of clearing away lung-heat.There were high significant differences between hollow roots and lateral root of Baikal Skullcap（P < 0.01）.Therefore

the quality evaluation criteria of hol-low roots and solid lateral root of Baikal Skullcap should be established separately.