ObjectiveTo investigate the therapeutic effects and mechanisms of modified Huangqi Jianzhong decoction （HQJZ） on gastric precancerous conditions （GPC）. MethodsIn the cell experiment， human gastric mucosal epithelial cells underwent malignant transformation induced by N-methyl-N′-nitro-N-nitrosoguanidine （MNNG） for the modeling of GPC （MC cells）. The cells were allocated into four groups： control ， model， low-dose HQJZ （HQJZ-L）， and high-dose HQJZ （HQJZ-H）. The control and model groups were cultured with the complete medium， while HQJZ-L and HQJZ-H groups received additional interventions with HQJZ at low （0.5 g·L^-1） and high （1.0 g·L^-1） doses， respectively. Cell counting kit-8 （CCK-8） assay was used to evaluate cytotoxicity， Transwell assay to assess cell invasion， Annexin V-FITC/PI staining to detect apoptosis， immunofluorescence assay to analyze reactive oxygen species （ROS） expression and mitochondrial autophagy， and Western blot to verify expression of proteins in key pathways. In the animal experiment， the GPC model was established in healthy BALB/c mice through MNNG induction. Twenty-four mice were allocated into four groups： control， model， HQJZ-L， and HQJZ-H. Control and model groups received normal saline （10 mL·kg^-1·d^-1） orally， while HQJZ-L and HQJZ-H groups were administrated with low-dose （6.24 g·kg^-1·d^-1） and high-dose （12.48 g·kg^-1·d^-1） HQJZ， respectively. After treatment， hematoxylin‑eosin （HE） staining and AB-PAS staining were performed to observe histopathological changes in the gastric tissue. Immunofluorescence assay was used to detect reactive oxygen species （ROS） and microtubule-associated protein 1 light chain 3 （LC3） levels in the gastric mucosa， TdT-mediated dUTP nick-end labeling （TUNEL） staining to assess apoptosis rates， and Western blotting and immunohistochemistry （IHC） to analyze the expression levels of Ki67， proliferating cell nuclear antigen （PCNA）， and foxhead box O3 （FoxO3）. ResultsCell viability assays showed that HQJZ dose-dependently reduced MC cell viability compared with the control group （P<0.05， P<0.01）. Transwell assays revealed that the model group exhibited enhanced cell invasion compared with the control group （P<0.05）. Compared with the model group， HQJZ treatment attenuated the cell invasion （P<0.05）. Gastric mucosal pathology in mice demonstrated that compared with the control group， the model group showed elevated HE and AB-PAS pathological scores （P<0.05）， while HQJZ treatment reduced these scores （P<0.05）. Transmission electron microscopy revealed increased mitochondrial number and volume in the model group compared with the control group. HQJZ treatment resulted in abnormal mitochondrial structure and significant alterations in rough endoplasmic reticulum morphology and distribution， presenting as dilated and hollow forms. Mitochondrial and apoptosis assessments indicated that compared with the control group， the model group exhibited enhanced Mito Tracker Green fluorescence （P<0.05）， no significant change in DCFH-DA fluorescence， Mito Tracker Red CMXRos fluorescence， ROS immunofluorescence， or malondialdehyde （MDA） level， increased GSH level （P<0.05）， enhanced LC3 fluorescence （P<0.05）， no significant change in apoptosis rate， and elevated ATP content in cells and mouse serum （P<0.05）. Compared with the model group， HQJZ treatment reduced Mito Tracker Green fluorescence （P<0.05）， increased DCFH-DA fluorescence， Mito Tracker Red fluorescence， MDA level， LC3 fluorescence， and apoptosis rate （P<0.05）， and decreased cellular ATP content （P<0.05）. The HQJZ-L group showed no significant change in ROS immunofluorescence or GSH level， whereas the HQJZ-H group demonstrated enhanced ROS immunofluorescence and glutathione （GSH） level （P<0.05）. Immunohistochemistry and Western blotting revealed that compared with the control group， the model group exhibited increased numbers of PCNA- and Ki67-positive cells （P<0.05） and elevated protein levels of FoxO3， sirtuin 1 （SIRT1）， and B-cell lymphoma 6 （Bcl-6） （P<0.05）. HQJZ treatment reduced the numbers of PCNA- and Ki67-positive cells （P<0.05） and lowered the protein levels of FoxO3， SIRT1， and Bcl-6 （P<0.05）. ConclusionHQJZ alleviates the progression of gastric precancerous lesions by regulating mitochondrial function via the FoxO3/ROS pathway and promoting apoptosis of GPC-malignant cells.