To observe the curative effect of modified Sijunzi tang based on routine western medicine on chronic atrophic gastritis(CAG)，and to analyze its effect on gene expressions of trefoil factor 2(TFF2)and nuclear factor- κB(NF-κB)in the gastric mucosa.Methods：A total of 84 cases of CAG patients of spleen-stomach weakness type were selected and randomly divided into the control group and the observation group，42 cases in each group.Both groups were treated with routine western medicine，and the observation group was additionally treated with modified Sijunzi tang.Both groups were treated for two courses，eight weeks being a course.The Chinese medicine symptom scores and expressiosn of gene TFF2 and NF-κB of the gastric mucosa tissues before and after treatment in the two groups were compared，the effect after treatment in the two groups were compared.Results：After treatment，the total effective rate in the observation group was higher than that in the control group(P ＜ 0.05).The scores of stuffiness and fullness，anorexia，stomachache and belching in the two groups were decreased when compared with those before treatment(P ＜ 0.05)，and the above four symptoms scores in the observation group were lower than those in the control group(P＜0.05).The gene expression levels of TFF2 in the gastric mucosa tissues in the two groups were increased when compared with those before treatment，while the ones of NF-κB were decreased when compared with those before treatment，differences being significant(P ＜ 0.05).The level of expression of gene TFF2 in the observation group was higher than that in the control group，and the level of gene NF-κB in the observation group was lower than that in the control group，differences being significant(P ＜ 0.05).There was no obvious adverse reaction in the two groups during the treatment.Conclusion：The therapy of modified Sijunzi tang based on routine western medicine can effectively reduce the clinical symptoms of CAG patients of spleen-stomach weakness type and promote the recovery of pathological changes in the gastric mucosa with significant curative effect and low incidence of adverse reactions，which can be an effective clinical treatment for CAG.