Objective: To determine the direct substance basis of Niuhuang Qinggan capsules by analyzing the temporal variation of transitional components in blood of Niuhuang Qinggan capsules.Methods: Guided by the theory of serum pharmacochem. of Traditional Chinese medicine and with uplC-Q-TOF-MS technol. as the core, the time-varying law of 12 blood transitional components with high relative content in rats after oral administration of Niuhuang Qinggan capsule was studied, and the changing law in vivo was analyzed and clarified.Results: Luteolin, cholic acid, phenylalanine, chlorogenic acid, bezocholic acid and glycine cholic acid have the characteristics of easy detection, rapid absorption, high concentration in blood, and long elimination time, and have good pharmacol. activities.These components were identified as the potential effective components of Niuhuang Qinggan capsule.Conclusion: The anal. of the temporal variation of the transitional components in blood can provide alternative compounds for the basic study of the pharmacodynamic substances of Niuhuang Qinggan capsules.