Objectives: Based on the famous Chinese herbal prescription Xiaochaihutang (XCHT) consisting of seven Chinese herbs,widely used for the treatment of various inflammatory disorders for thousand years in China,modified XCHT has been used clinically in gastritis in Hospital of Traditional Chinese Medicine for several years in Chinas south city.In this research,modified XCHT was investigated to confirm the anti-helicobacter pylori (H.Pylori) and anti-inflammatory effects,the main constituents of different extracts for elaborating its pharmacodynamic material basis,and providing a scientific basis for the treatment of gastritis clinically.Methods: To identify the effective fractions for pharmacological activities,the full prescription was separated to five fractions by systematic solvent extraction to volatile oil fraction,water extracts,CHCl3 extracts,EtOAc extracts,and n-BuOH extracts.The activity of full prescription and different extracts towards H.pylori was assessed by agar diffusion method in vitro,and the minimal inhibitory concentration (MIC) was also determined by fluid dilution method.The activity of full prescription and different extracts towards inflammatory were assessed by the animal model of mouse ear edema induced by xylene and rat paw edema induced by carrageenin.Chemical profile of active constituents in plasma after oral administration of the active extracts of modified XCHT was revealed by high performance liquid chromatography-time of flight-mass spectrometry (HPLC-TOF-MS/MS).Results: The bacterial inhibition diameter and MIC of the full prescription were (6.90±0.63) mm and 125mg/mL of the crude drug,the bacterial inhibition diameter and MIC of the volatile oil fraction were (7.46±0.47) mm and 500mg/mL of the crude drug,the bacterial inhibition diameter and MIC of CHCl3 extracts were (7.28±0.21) mm and 130mg/mL of the crude drug,the bacterial inhibition diameter and MIC of EtOAc extracts were (7.46±0.10) mm and 506mg/mL of the crude drug,the bacterial inhibition diameter and MIC of n-BuOH extracts were (7.29±0.10) mm and 246mg/mL of the crude drug.Xylene-induced mouse ear edema model,high and low dose group of the full prescription and n-BuOH extracts,high dose group of water extracts could very significantly inhibit the mouse ear edema (P<0.01);high dose group of EtOAc extracts could significantly inhibit the mouse ear edema (P<0.05).Carrageenan-induced rat paw edema model,high and low dose group of the full prescription and n-BuOH extracts,high dose group of EtOAc extracts could very significantly inhibit the rat paw edema (P<0.01);high dose group of water extracts could significant reduce paw swelling of rats (P<0.05).A total 8 active constituents in plasma,including 4 prototype components and 4 metabolites,were identified by HPLC-TOF-MS/MS after oral administration of EtOAc extracts.In addition,a total 12 active constituents in plasma,including 6 prototype components and 6 metabolites,were identified by HPLC-TOF-MS/MS after oral administration of n-BuOH extracts.Conclusion: The present results reveal that EtOAc extracts and n-BuOH extracts were effective fractions for anti-H.Pylori and anti-inflammatory in modified XCHT,and also provide experiment data for the clinical treatment of chronic gastritis.